parser: wordsmith diagnostic message

Address post-commit commit about the wording of the warning.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@239879 91177308-0d34-0410-b5e6-96231b3b80d8

include/clang/Basic/DiagnosticParseKinds.td

@@ -1001,7 +1001,8 @@ def warn_pragma_unroll_cuda_value_in_parens : Warning<
   "argument to '#pragma unroll' should not be in parentheses in CUDA C/C++">,
   InGroup<CudaCompat>;
 
-def err_empty_attribute_block : Error<"empty attribute block is not allowed">;
+def err_empty_attribute_block : Error<
+  "Microsoft attribute block cannot be empty">;
 
 } // end of Parse Issue category.
 

test/Parser/MicrosoftExtensions.c

@@ -55,7 +55,7 @@ int foo1([SA_Post(attr=1)] void *param);
 [unbalanced(attribute) /* expected-note {{to match this '['}} */
 void f(void); /* expected-error {{expected ']'}} */
 
-[] __interface I {}; /* expected-error {{empty attribute block is not allowed}} */
+[] __interface I {}; /* expected-error {{Microsoft attribute block cannot be empty}} */
 
 void ms_intrinsics(int a) {
   __noop();