[PATCH] libsanitizer merge from upstream r208536 fix for ARM Linux.

[Kostya Serebryany]

================
Comment at: sanitizer_common/sanitizer_atomic_clang_other.h:56
@@ -55,3 +55,3 @@
     // Assume that it is not in read-only memory.
-    v = __sync_fetch_and_add((typename T::Type volatile*)&a->val_dont_use, 0);
+    v = __sync_fetch_and_add(const_cast<typename T::Type volatile*>(&a->val_dont_use), 0);
   }
----------------
<= 80 chars

http://reviews.llvm.org/D3737