android: virgl: fix generated virgl_driinfo.h building rules

Changelog in Android makefile:
- Add LOCAL_MODULE_CLASS, intermediates and LOCAL_GENERATED_SOURCES
- Use LOCAL_EXPORT_C_INCLUDE_DIRS to export $(intermediates) path
- Move generated header rules before 'include $(BUILD_STATIC_LIBRARY)'

Fixes the following building error:

In file included from external/mesa/src/gallium/targets/dri/target.c:1:
external/mesa/src/gallium/auxiliary/target-helpers/drm_helper.h:257:16:
fatal error: 'virgl/virgl_driinfo.h' file not found
      #include "virgl/virgl_driinfo.h"
               ^~~~~~~~~~~~~~~~~~~~~~~
1 error generated.

Fixes: cf800998a ("virgl: Add driinfo file and tie it into the build")
Signed-off-by: Mauro Rossi <issor.oruam@gmail.com>
Review-by: Chih-Wei Huang <cwhuang@linux.org.tw>

src/gallium/drivers/virgl/Android.mk

@@ -30,8 +30,9 @@ LOCAL_SRC_FILES := \
 
 LOCAL_MODULE := libmesa_pipe_virgl
 
-include $(GALLIUM_COMMON_MK)
-include $(BUILD_STATIC_LIBRARY)
+LOCAL_MODULE_CLASS := STATIC_LIBRARIES
+intermediates := $(call local-generated-sources-dir)
+LOCAL_GENERATED_SOURCES := $(intermediates)/virgl/virgl_driinfo.h
 
 GEN_DRIINFO_INPUTS := \
 	$(MESA_TOP)/src/gallium/auxiliary/pipe-loader/driinfo_gallium.h \
@@ -44,6 +45,11 @@ $(intermediates)/virgl/virgl_driinfo.h: $(MERGE_DRIINFO) $(GEN_DRIINFO_INPUTS)
 	@echo "Gen Header: $(PRIVATE_MODULE) <= $(notdir $(@))"
 	$(hide) $(MESA_PYTHON2) $(MERGE_DRIINFO) $(GEN_DRIINFO_INPUTS) > $@ || ($(RM) $@; false)
 
+LOCAL_EXPORT_C_INCLUDE_DIRS := $(intermediates)
+
+include $(GALLIUM_COMMON_MK)
+include $(BUILD_STATIC_LIBRARY)
+
 ifneq ($(HAVE_GALLIUM_VIRGL),)
 GALLIUM_TARGET_DRIVERS += virtio_gpu
 $(eval GALLIUM_LIBS += $(LOCAL_MODULE) libmesa_winsys_virgl_common libmesa_winsys_virgl libmesa_winsys_virgl_vtest)