[sanitizer] Move the errno/ENOMEM allocator checks logic to separate .cc

[cryptoad]

Summary

This is a new attempt at D38706, which had 2 issues.

The first one was that it broke TSan, because sanitizer_errno.h was not
directly included in tsan_mman.cc. This fixes the include.

The second one was that it broke the nolibc build, because __errno_location
couldn't be found. This adds the new .cc to the libcdep list instead of the
base one.

lib/sanitizer_common/CMakeLists.txt

 # Libc functions stubs. These sources should be linked instead of
 # SANITIZER_LIBCDEP_SOURCES when sanitizer_common library must not depend on
 # libc.
 set(SANITIZER_NOLIBC_SOURCES
   sanitizer_common_nolibc.cc)
 
 set(SANITIZER_LIBCDEP_SOURCES
   sanitizer_common_libcdep.cc
+  sanitizer_allocator_checks.cc
   sancov_flags.cc
   sanitizer_coverage_fuchsia.cc
   sanitizer_coverage_libcdep_new.cc
   sanitizer_coverage_win_sections.cc
   sanitizer_linux_libcdep.cc
   sanitizer_mac_libcdep.cc
   sanitizer_posix_libcdep.cc
   sanitizer_stacktrace_libcdep.cc

lib/sanitizer_common/sanitizer_allocator_checks.h

 // Various checks shared between ThreadSanitizer, MemorySanitizer, etc. memory
 // allocators.
 //
 //===----------------------------------------------------------------------===//
 
 #ifndef SANITIZER_ALLOCATOR_CHECKS_H
 #define SANITIZER_ALLOCATOR_CHECKS_H
 
-#include "sanitizer_errno.h"
 #include "sanitizer_internal_defs.h"
 #include "sanitizer_common.h"
 #include "sanitizer_platform.h"
 
 namespace __sanitizer {
 
+// The following is defined in a separate compilation unit to avoid pulling in
+// sanitizer_errno.h in this header, which leads to conflicts when other system
+// headers include errno.h. This is usually the result of an unlikely event,
+// and as such we do not care as much about having it inlined.
+void SetErrnoToENOMEM();
+
 // A common errno setting logic shared by almost all sanitizer allocator APIs.
 INLINE void *SetErrnoOnNull(void *ptr) {
   if (UNLIKELY(!ptr))
-    errno = errno_ENOMEM;
+    SetErrnoToENOMEM();
   return ptr;
 }
 
 // In case of the check failure, the caller of the following Check... functions
 // should "return POLICY::OnBadRequest();" where POLICY is the current allocator
 // failure handling policy.
 
 // Checks aligned_alloc() parameters, verifies that the alignment is a power of

lib/sanitizer_common/sanitizer_allocator_checks.cc

+//===-- sanitizer_allocator_checks.cc ---------------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// Various checks shared between ThreadSanitizer, MemorySanitizer, etc. memory
+// allocators.
+//
+//===----------------------------------------------------------------------===//
+
+#include "sanitizer_errno.h"
+
+namespace __sanitizer {
+
+void SetErrnoToENOMEM() {
+  errno = errno_ENOMEM;
+}
+
+} // namespace __sanitizer

lib/tsan/rtl/tsan_mman.cc

 //===-- tsan_mman.cc ------------------------------------------------------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 //
 // This file is a part of ThreadSanitizer (TSan), a race detector.
 //
 //===----------------------------------------------------------------------===//
 #include "sanitizer_common/sanitizer_allocator_checks.h"
 #include "sanitizer_common/sanitizer_allocator_interface.h"
 #include "sanitizer_common/sanitizer_common.h"
+#include "sanitizer_common/sanitizer_errno.h"
 #include "sanitizer_common/sanitizer_placement_new.h"
 #include "tsan_mman.h"
 #include "tsan_rtl.h"
 #include "tsan_report.h"
 #include "tsan_flags.h"
 
 // May be overriden by front-end.
 SANITIZER_WEAK_DEFAULT_IMPL