revert r354873 as this breaks lldb builds.

llvm-svn: 354875
diff --git a/clang/lib/Sema/SemaDeclAttr.cpp b/clang/lib/Sema/SemaDeclAttr.cpp
index d312936..bf11ae9 100644
--- a/clang/lib/Sema/SemaDeclAttr.cpp
+++ b/clang/lib/Sema/SemaDeclAttr.cpp
@@ -6211,8 +6211,7 @@
     if (!S.checkStringLiteralArgumentAttr(AL, I, SanitizerName, &LiteralLoc))
       return;
 
-    if (parseSanitizerValue(SanitizerName, /*AllowGroups=*/true) ==
-        SanitizerMask())
+    if (parseSanitizerValue(SanitizerName, /*AllowGroups=*/true) == 0)
       S.Diag(LiteralLoc, diag::warn_unknown_sanitizer_ignored) << SanitizerName;
     else if (isGlobalVar(D) && SanitizerName != "address")
       S.Diag(D->getLocation(), diag::err_attribute_wrong_decl_type)