Silence a warning.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@26508 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/utils/TableGen/FileLexer.l b/utils/TableGen/FileLexer.l
index c561ec6..020a356 100644
--- a/utils/TableGen/FileLexer.l
+++ b/utils/TableGen/FileLexer.l
@@ -128,7 +128,7 @@
     std::string NextFilename;
     for (unsigned i = 0, e = IncludeDirectories.size(); i != e; ++i) {
       NextFilename = IncludeDirectories[i] + "/" + Filename;
-      if (yyin = fopen(NextFilename.c_str(), "r"))
+      if ((yyin = fopen(NextFilename.c_str(), "r")))
         break;
     }