Switch LLVM_USE_RVALUE_REFERENCES to LLVM_HAS_RVALUE_REFERENCES.

Rationale:
1) This was the name in the comment block. ;]
2) It matches Clang's __has_feature naming convention.
3) It matches other compiler-feature-test conventions.

Sorry for the noise. =]

I've also switch the comment block to use a \brief tag and not duplicate
the name.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@168996 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Support/LocaleWindows.inc b/lib/Support/LocaleWindows.inc
index 6827ac1..28e429c 100644
--- a/lib/Support/LocaleWindows.inc
+++ b/lib/Support/LocaleWindows.inc
@@ -12,4 +12,4 @@
 
 }
 }
-}
\ No newline at end of file
+}