Vlv2TbltDevicePkg: Only define MDEPKG_NDEBUG for gcc release build

We only enable "-Wno-unused-but-set-variable" for the release build
and gcc would complain that the varible passed to ASSERT_EFI_ERROR
wasn't used in the debug build. Just don't define MDEPKG_NDEBUG for
the debug build to make gcc happy with ASSERT_EFI_ERROR.

Suggested-by: Laszlo Ersek <lersek@redhat.com>
Cc: David Wei <david.wei@intel.com>
CC: Laszlo Ersek <lersek@redhat.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Gary Lin <glin@suse.com>
diff --git a/Vlv2TbltDevicePkg/PlatformPkgGccX64.dsc b/Vlv2TbltDevicePkg/PlatformPkgGccX64.dsc
index 9865785..05eb3c6 100644
--- a/Vlv2TbltDevicePkg/PlatformPkgGccX64.dsc
+++ b/Vlv2TbltDevicePkg/PlatformPkgGccX64.dsc
@@ -1091,7 +1091,7 @@
     !endif

        <BuildOptions>

         ICC:*_*_*_CC_FLAGS = -D MDEPKG_NDEBUG

-        GCC:*_*_*_CC_FLAGS = -D MDEPKG_NDEBUG

+        GCC:RELEASE_*_*_CC_FLAGS = -D MDEPKG_NDEBUG

   }

   MdeModulePkg/Universal/PCD/Dxe/Pcd.inf {

     <LibraryClasses>