Fix grammar

Author: thurstond

clang/lib/CodeGen/CGExpr.cpp

@@ -4000,7 +4000,7 @@ void CodeGenFunction::EmitCfiCheckFail() {
       IntPtrTy);
 
   // TODO: the instructions above are not annotated with debug info. It is
-  // inconvenient to do so because we hadn't determined the SanitizerKind yet.
+  // inconvenient to do so because we have not determined SanitizerKind yet.
   const std::pair<int, SanitizerKind::SanitizerOrdinal> CheckKinds[] = {
       {CFITCK_VCall, SanitizerKind::SO_CFIVCall},
       {CFITCK_NVCall, SanitizerKind::SO_CFINVCall},