android: virgl: fix generated virgl_driinfo.h building rules

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>