make with-android-headers optional

If --with-android-headers is not specified, try to use pkg-config.

Also, extract Android versions from android-version.h using
ANDROID_HEADERS_CFLAGS and the preprocessor.

Signed-off-by: Adrian Negreanu <adrian.m.negreanu@intel.com>
Don't use the android/ prefix in #includes
Ensure all Makefile.am have ANDROID_HEADERS_CFLAGS to avoid the android/ prefix in #include

[adrian] use ANDROID_HEADERS_CFLAGS instead of '-Itop_srcdir/include/android -Itop_srcdir/include/android/libnfc-nxp'

Signed-off-by: David Greaves <david@dgreaves.com>
Signed-off-by: Adrian Negreanu <adrian.m.negreanu@intel.com>
remove unused gralloc param

Signed-off-by: Adrian Negreanu <adrian.m.negreanu@intel.com>
remove un-defined egl_create_image_wl

Signed-off-by: Adrian Negreanu <adrian.m.negreanu@intel.com>
Merge pull request #195 from groleo/cleanups

Cleanups