Android: glsl: fix dependence on YACC_HEADER_SUFFIX from build system

The makefile was implicitly picking up YACC_HEADER_SUFFIX from the Android
build system, but this variable is now gone. Add it locally to fix the
build with AOSP master.

Cc: "11.1 11.2" <mesa-stable@lists.freedesktop.org>
Signed-off-by: Rob Herring <robh@kernel.org>
Reviewed-by: Emil Velikov <emil.velikov@collabora.com>

src/compiler/glsl/Android.gen.mk

@@ -51,6 +51,8 @@ define glsl_local-y-to-c-and-h
 	$(hide) $(YACC) -o $@ -p "glcpp_parser_" $<
 endef
 
+YACC_HEADER_SUFFIX := .hpp
+
 define local-yy-to-cpp-and-h
 	@mkdir -p $(dir $@)
 	@echo "Mesa Yacc: $(PRIVATE_MODULE) <= $<"