Revert "Add [[clang::nomerge]] attribute to ~CheckError()."

This reverts commit 88602533.

Reason for revert:

Findit (https://goo.gl/kROfz5) identified CL at revision 844989 as the
culprit for failures in the build cycles as shown on:
https://analysis.chromium.org/waterfall/culprit?key=ag9zfmZpbmRpdC1mb3ItbWVyRAsSDVdmU3VzcGVjdGVkQ0wiMWNocm9taXVtLzg4NjAyNTMzNzZjMzhjMDkwZDU4NWJkYTRiMjBiODAxZTNhYTNjZTMM

Sample Failed Build: https://ci.chromium.org/b/8857616434338832304

Sample Failed Step: compile

Original change's description:
> Add [[clang::nomerge]] attribute to ~CheckError().
> 
> To disable merging multiple ~CheckError() destructor for accurate crash logs.
> 
> Bug: 1153188
> Change-Id: If6d153661667a63f13b645f6d284eb3d5ea3a300
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2611331
> Commit-Queue: Nico Weber <thakis@chromium.org>
> Auto-Submit: Zequan Wu <zequanwu@google.com>
> Reviewed-by: Nico Weber <thakis@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#844989}


Change-Id: I8909aed272fc0c480f07a6c607f1ca5f65343c9c
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 1153188
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2639533
Cr-Commit-Position: refs/heads/master@{#845015}

base/check.h

@@ -85,7 +85,7 @@ class BASE_EXPORT CheckError {
   // Stream for adding optional details to the error message.
   std::ostream& stream();
 
-  NOMERGE ~CheckError();
+  ~CheckError();
 
   CheckError(const CheckError& other) = delete;
   CheckError& operator=(const CheckError& other) = delete;

base/compiler_specific.h

@@ -332,11 +332,4 @@ inline constexpr bool AnalyzerAssumeTrue(bool arg) {
 
 #endif  // defined(__clang_analyzer__)
 
-// Use nomerge attribute to disable optimization of merging multiple same calls.
-#if defined(__clang__) && __has_attribute(nomerge) && !defined(OS_CHROMEOS)
-#define NOMERGE [[clang::nomerge]]
-#else
-#define NOMERGE
-#endif
-
 #endif  // BASE_COMPILER_SPECIFIC_H_