extract-headers.sh: better support for packagers

* Add Makefile so we only need to extract the headers one, but
  be able to install it in different locations.

* Replace -p|--pkgincludedir with make install option, PREFIX

* Place all headers in HEADER_DIR/src and support files under HEADER_DIR
  This makes it easy for make install to just cp -r src/* dest-dir

Signed-off-by: Adrian Negreanu <adrian.m.negreanu@intel.com>
make with-android-headers optional

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

Then, extract Android versions from android-version.h but take
ANDROID_HEADERS_CFLAGS into account.

Signed-off-by: Adrian Negreanu <adrian.m.negreanu@intel.com>
replace -I/include/android with ANDROID_HEADERS_CFLAGS

Signed-off-by: Adrian Negreanu <adrian.m.negreanu@intel.com>
hwcomposer-egl.pc: link with hybris-hardware

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