[TSan][libdispatch] Remove dependency on system headers

[yln]

Summary

Including <dispatch/dispatch.h> and <Blocks.h> transitively pulls in
other system headers. Let's try to avoid that.

Blocks.h: compiler-rt already includes a blocks runtime. Just use the
header file that comes with it.

dispatch.h: Declare the bare minimum required for our implementation,
i.e., everything needed to define the interceptors, but not the
interceptors themselves. See tsan_dispatch_defs.h. I spotted a few other
places in compile-rt, where we declare libdispatch types. Maybe this
file can be moved to sanitizer_common if we deem it useful enough.

tsan_libdispatch.cc now compiles on Linux/Clang (requires support for
-fblocks). Linking still requires some manual configuration.

[yln]

@dvyukov *ping*

[kubamracek]

Looks good, with a nit (feel free to address it separately).

compiler-rt/lib/tsan/rtl/tsan_dispatch_defs.h

53–56

Can we just unconditionally define DISPATCH_NOESCAPE now that we don't include the system header?

[yln]

compiler-rt/lib/tsan/rtl/tsan_dispatch_defs.h

53–56

Will define by copying from:
https://github.com/apple/swift-corelibs-libdispatch/blob/bc00e13bc7e912d4d9028df2a0b2bfa4c0e11323/dispatch/base.h#L200

compiler-rt/lib/tsan/rtl/tsan_dispatch_defs.h

+//===-- tsan_dispatch_defs.h ------------------------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file is a part of ThreadSanitizer (TSan), a race detector.
+//
+//===----------------------------------------------------------------------===//
+#ifndef TSAN_DISPATCH_DEFS_H
+#define TSAN_DISPATCH_DEFS_H
+
+#include "sanitizer_common/sanitizer_internal_defs.h"
+
+typedef struct dispatch_object_s {} *dispatch_object_t;
+
+#define DISPATCH_DECL(name) \
+  typedef struct name##_s : public dispatch_object_s {} *name##_t
+
+DISPATCH_DECL(dispatch_queue);
+DISPATCH_DECL(dispatch_source);
+DISPATCH_DECL(dispatch_group);
+DISPATCH_DECL(dispatch_data);
+DISPATCH_DECL(dispatch_semaphore);
+DISPATCH_DECL(dispatch_io);
+
+typedef void (*dispatch_function_t)(void *arg);
+typedef void (^dispatch_block_t)(void);
+typedef void (^dispatch_io_handler_t)(bool done, dispatch_data_t data,
+                                      int error);
+
+typedef long dispatch_once_t; // NOLINT
+typedef __sanitizer::u64 dispatch_time_t;
+typedef int dispatch_fd_t; // NOLINT
+typedef unsigned long dispatch_io_type_t; // NOLINT
+typedef unsigned long dispatch_io_close_flags_t; // NOLINT
+
+extern "C" {
+void *dispatch_get_context(dispatch_object_t object);
+void dispatch_retain(dispatch_object_t object);
+void dispatch_release(dispatch_object_t object);
+
+extern const dispatch_block_t _dispatch_data_destructor_free;
+extern const dispatch_block_t _dispatch_data_destructor_munmap;
+} // extern "C"
+
+#define DISPATCH_DATA_DESTRUCTOR_DEFAULT nullptr
+#define DISPATCH_DATA_DESTRUCTOR_FREE    _dispatch_data_destructor_free
+#define DISPATCH_DATA_DESTRUCTOR_MUNMAP  _dispatch_data_destructor_munmap
+
+// DISPATCH_NOESCAPE is only defined on Apple platforms with at least Xcode 8.
+#ifndef DISPATCH_NOESCAPE
+#define DISPATCH_NOESCAPE
+#endif
+
+// Data types used in dispatch APIs
+typedef unsigned long size_t; // NOLINT
+typedef unsigned long uintptr_t; // NOLINT
+typedef __sanitizer::s64 off_t;
+typedef __sanitizer::u16 mode_t;
+typedef long long_t; // NOLINT
+
+#endif  // TSAN_DISPATCH_DEFS_H

compiler-rt/lib/tsan/rtl/tsan_libdispatch.cc

 //===-- tsan_libdispatch.cc -----------------------------------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 //
 // This file is a part of ThreadSanitizer (TSan), a race detector.
 //
 // Support for intercepting libdispatch (GCD).
 //===----------------------------------------------------------------------===//
 
-#include "sanitizer_common/sanitizer_platform.h"
-
 #include "sanitizer_common/sanitizer_common.h"
 #include "interception/interception.h"
 #include "tsan_interceptors.h"
-#include "tsan_platform.h"
 #include "tsan_rtl.h"
 
-#include <Block.h>
-#include <dispatch/dispatch.h>
-
-// DISPATCH_NOESCAPE is only defined on Apple platforms with at least Xcode 8.
-#ifndef DISPATCH_NOESCAPE
-#define DISPATCH_NOESCAPE
-#endif
-
-typedef long long_t;  // NOLINT
+#include "BlocksRuntime/Block.h"
+#include "tsan_dispatch_defs.h"
 
 namespace __tsan {
+  typedef u16 uint16_t;
 
 typedef struct {
   dispatch_queue_t queue;
   void *orig_context;
   dispatch_function_t orig_work;
   bool free_context_in_callback;
   bool submitted_synchronously;
   bool is_barrier_block;

 TSAN_INTERCEPTOR(long_t, dispatch_group_wait, dispatch_group_t group,
                  dispatch_time_t timeout) {
   SCOPED_TSAN_INTERCEPTOR(dispatch_group_wait, group, timeout);
   long_t result = REAL(dispatch_group_wait)(group, timeout);
   if (result == 0) Acquire(thr, pc, (uptr)group);
   return result;
 }
 
+// Used, but not intercepted.
+extern "C" void dispatch_group_enter(dispatch_group_t group);
+
 TSAN_INTERCEPTOR(void, dispatch_group_leave, dispatch_group_t group) {
   SCOPED_TSAN_INTERCEPTOR(dispatch_group_leave, group);
-  // Acquired in the group noticifaction callback in dispatch_group_notify[_f].
+  // Acquired in the group notification callback in dispatch_group_notify[_f].
   Release(thr, pc, (uptr)group);
   REAL(dispatch_group_leave)(group);
 }
 
 TSAN_INTERCEPTOR(void, dispatch_group_async, dispatch_group_t group,
                  dispatch_queue_t queue, dispatch_block_t block) {
   SCOPED_TSAN_INTERCEPTOR(dispatch_group_async, group, queue, block);
   dispatch_retain(group);
   dispatch_group_enter(group);
-  __block dispatch_block_t block_copy = (dispatch_block_t)_Block_copy(block);
+  __block dispatch_block_t block_copy = (dispatch_block_t)Block_copy(block);
   WRAP(dispatch_async)(queue, ^(void) {
     block_copy();
-    _Block_release(block_copy);
+    Block_release(block_copy);
     WRAP(dispatch_group_leave)(group);
     dispatch_release(group);
   });
 }
 
 TSAN_INTERCEPTOR(void, dispatch_group_async_f, dispatch_group_t group,
                  dispatch_queue_t queue, void *context,
                  dispatch_function_t work) {