RedirectingFileSystem::openFileForRead - replace bitwise & with boolean && to fix warning

Seems to be just a typo - now matches other instances which do something similar

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@374995 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Support/VirtualFileSystem.cpp

@@ -1764,7 +1764,7 @@ ErrorOr<std::unique_ptr<File>>
 RedirectingFileSystem::openFileForRead(const Twine &Path) {
   ErrorOr<RedirectingFileSystem::Entry *> E = lookupPath(Path);
   if (!E) {
-    if (shouldUseExternalFS() &
+    if (shouldUseExternalFS() &&
         E.getError() == llvm::errc::no_such_file_or_directory) {
       return ExternalFS->openFileForRead(Path);
     }