Add noOverride64GlobalCflags support to Soong

Bug: b/261642850
Test: Build and check warnings. Add two xfail tests in bionic and see the
results locally.

Change-Id: I68fca0084787c329b6c49ce4dff6fd132f820735
diff --git a/cc/makevars.go b/cc/makevars.go
index c70d4a6..6c3f551 100644
--- a/cc/makevars.go
+++ b/cc/makevars.go
@@ -93,6 +93,7 @@
 
 	ctx.Strict("CLANG_EXTERNAL_CFLAGS", "${config.ExternalCflags}")
 	ctx.Strict("GLOBAL_CLANG_CFLAGS_NO_OVERRIDE", "${config.NoOverrideGlobalCflags}")
+	ctx.Strict("GLOBAL_CLANG_CFLAGS_64_NO_OVERRIDE", "${config.NoOverride64GlobalCflags}")
 	ctx.Strict("GLOBAL_CLANG_CPPFLAGS_NO_OVERRIDE", "")
 	ctx.Strict("GLOBAL_CLANG_EXTERNAL_CFLAGS_NO_OVERRIDE", "${config.NoOverrideExternalGlobalCflags}")