Do not redefine the THREAD_ANNOTATION_ATTRIBUTE__ macro in the documentation.

Patch by Roman Lebedev.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@302275 91177308-0d34-0410-b5e6-96231b3b80d8

docs/ThreadSafetyAnalysis.rst

@@ -764,8 +764,6 @@ implementation.
   #define THREAD_ANNOTATION_ATTRIBUTE__(x)   // no-op
   #endif
 
-  #define THREAD_ANNOTATION_ATTRIBUTE__(x)   __attribute__((x))
-
   #define CAPABILITY(x) \
     THREAD_ANNOTATION_ATTRIBUTE__(capability(x))