[Darwin][Sanitizers][CrashReporter] Adopt initializer for Crash Reporter Annotations struct (llvm#123978)

An initializer for the Crash Reporter Annotatoins struct was added in
version 5. For the simplicity of not needing to always update the struct
in subsequent versions, this patchs checks for the initializer before
attempting to redefine the struct on its own.

Note -- we have an existing test for this that is disabled by default,
it is inherently flakey due to the nature of crash reporter. But we can
run that when making crash reporter related changes.

rdar://136156203

Author: thetruestblue

compiler-rt/lib/sanitizer_common/sanitizer_mac.cpp

@@ -45,7 +45,7 @@ extern char **environ;
 #    define SANITIZER_OS_TRACE 0
 #  endif
 
-// import new crash reporting api
+// Integrate with CrashReporter library if available
 #  if defined(__has_include) && __has_include(<CrashReporterClient.h>)
 #    define HAVE_CRASHREPORTERCLIENT_H 1
 #    include <CrashReporterClient.h>
@@ -796,8 +796,13 @@ static char crashreporter_info_buff[__sanitizer::kErrorMessageBufferSize] = {};
 static Mutex crashreporter_info_mutex;
 
 extern "C" {
-// Integrate with crash reporter libraries.
+
 #if HAVE_CRASHREPORTERCLIENT_H
+// Available in CRASHREPORTER_ANNOTATIONS_VERSION 5+
+#    ifdef CRASHREPORTER_ANNOTATIONS_INITIALIZER
+CRASHREPORTER_ANNOTATIONS_INITIALIZER()
+#    else
+// Support for older CrashRerporter annotiations
 CRASH_REPORTER_CLIENT_HIDDEN
 struct crashreporter_annotations_t gCRAnnotations
     __attribute__((section("__DATA," CRASHREPORTER_ANNOTATIONS_SECTION))) = {
@@ -808,17 +813,17 @@ struct crashreporter_annotations_t gCRAnnotations
         0,
         0,
         0,
-#if CRASHREPORTER_ANNOTATIONS_VERSION > 4
+#      if CRASHREPORTER_ANNOTATIONS_VERSION > 4
         0,
-#endif
+#      endif
 };
-
-#else
-// fall back to old crashreporter api
+#    endif
+#  else
+// Revert to previous crash reporter API if client header is not available
 static const char *__crashreporter_info__ __attribute__((__used__)) =
     &crashreporter_info_buff[0];
 asm(".desc ___crashreporter_info__, 0x10");
-#endif
+#endif  // HAVE_CRASHREPORTERCLIENT_H
 
 }  // extern "C"