Add declaration for `__tsan_default_options` to tsan_interface.h

[dmaclach]

Summary

__tsan_default_options is part of the tsan interface so should be exposed in tsan_interface.h.

[vitalybuka]

SANITIZER_WEAK_DEFAULT_IMPL on go is NOOP

[vitalybuka]

Add SANITIZER_WEAK_ATTRIBUTE

[vitalybuka]

We need TSAN_EXTERNAL_HOOKS for GO

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

35

SANITIZER_INTERFACE_ATTRIBUTE SANITIZER_WEAK_ATTRIBUTE const char* __tsan_default_options();

compiler-rt/lib/tsan/rtl/tsan_flags.cpp

 //===-- tsan_flags.cpp ----------------------------------------------------===//
 //
 // 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.
 //
 //===----------------------------------------------------------------------===//
 
-#include "sanitizer_common/sanitizer_flags.h"
+#include "tsan_flags.h"
+
 #include "sanitizer_common/sanitizer_flag_parser.h"
+#include "sanitizer_common/sanitizer_flags.h"
 #include "sanitizer_common/sanitizer_libc.h"
-#include "tsan_flags.h"
-#include "tsan_rtl.h"
+#include "tsan_interface.h"
 #include "tsan_mman.h"
+#include "tsan_rtl.h"
 #include "ubsan/ubsan_flags.h"
 
 namespace __tsan {
 
 // Can be overriden in frontend.
 #ifdef TSAN_EXTERNAL_HOOKS
-extern "C" const char* __tsan_default_options();
+extern "C" const char *__tsan_default_options();
 #else
 SANITIZER_WEAK_DEFAULT_IMPL
 const char *__tsan_default_options() {
   return "";
 }
 #endif
 
 void Flags::SetDefaults() {

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

 #endif
 
 #if !SANITIZER_GO
 
 // This function should be called at the very beginning of the process,
 // before any instrumented code is executed and before any call to malloc.
 SANITIZER_INTERFACE_ATTRIBUTE void __tsan_init();
 
+SANITIZER_INTERFACE_ATTRIBUTE SANITIZER_WEAK_ATTRIBUTE const char *
+__tsan_default_options();
+
 SANITIZER_INTERFACE_ATTRIBUTE void __tsan_flush_memory();
 
 SANITIZER_INTERFACE_ATTRIBUTE void __tsan_read1(void *addr);
 SANITIZER_INTERFACE_ATTRIBUTE void __tsan_read2(void *addr);
 SANITIZER_INTERFACE_ATTRIBUTE void __tsan_read4(void *addr);
 SANITIZER_INTERFACE_ATTRIBUTE void __tsan_read8(void *addr);
 SANITIZER_INTERFACE_ATTRIBUTE void __tsan_read16(void *addr);