VfrCompile: fix invalid comparison between pointer and integer

This would be valid C but is not valid C++, so change the comparison to do what it has always been doing.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Yonghong Zhu <yonghong.zhu@intel.com>
diff --git a/BaseTools/Source/C/VfrCompile/VfrUtilityLib.cpp b/BaseTools/Source/C/VfrCompile/VfrUtilityLib.cpp
index 3ca57ed..2f97975 100644
--- a/BaseTools/Source/C/VfrCompile/VfrUtilityLib.cpp
+++ b/BaseTools/Source/C/VfrCompile/VfrUtilityLib.cpp
@@ -3372,7 +3372,7 @@
   UINT8       BlockType;

   EFI_HII_STRING_PACKAGE_HDR *PkgHeader;

   

-  if (mStringFileName == '\0' ) {

+  if (mStringFileName == NULL) {

     return NULL;

   }