ndk-build: keep linking to GSTREAMER_EXTRA_LIBS explicitly
When removing hogweed linkage for gio workaround, the $GSTREAMER_EXTRA_LIBS
entry got removed from GSTREAMER_ANDROID_LIBS as well. Add it back, so it
works as intended in commit d4d75a04 and needed linkages like EGL work
again via GSTREAMER_EXTRA_LIBS -l
entries (instead of having to workaround
via TARGET_LDFLAGS).
Fixes: e3892148