android: Add camera metadata library

Import the Android camera metadata library from the ChromiumOS build
system.

The camera metadata library has been copied from
https://chromium.googlesource.com/chromiumos/platform2
at revision 9e65ddd2c496e712f005ada9715decd2ff8e4a03

The original path in the Cros platform2/ repository is:
camera/android/libcamera_metadata/src

Create a new build target for the camera metadata library to
create a static library to link against libcamera.

Signed-off-by: Jacopo Mondi <jacopo@jmondi.org>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

src/android/meson.build

@@ -0,0 +1,7 @@
+android_camera_metadata_sources = files([
+    'metadata/camera_metadata.c',
+])
+
+android_camera_metadata = static_library('camera_metadata',
+                                         android_camera_metadata_sources,
+                                         include_directories : android_includes)

src/meson.build

@@ -1,3 +1,4 @@
+subdir('android')
 subdir('libcamera')
 subdir('ipa')
 subdir('cam')