Fix typo. Extracted from the Andy/PaX patch.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@162281 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/MC/MCParser/AsmParser.cpp b/lib/MC/MCParser/AsmParser.cpp
index b67c769..7752bf2 100644
--- a/lib/MC/MCParser/AsmParser.cpp
+++ b/lib/MC/MCParser/AsmParser.cpp
@@ -1581,7 +1581,7 @@
     Lex();
   }
   if (ParenLevel != 0)
-    return TokError("unbalanced parenthesises in macro argument");
+    return TokError("unbalanced parentheses in macro argument");
   return false;
 }