Allow WRITE_SECURE_SETTINGS for ANGLE to provide developer options.

ANGLE is a system library which adds a developer option to control when
it is used as the default OpenGL ES driver.

ANGLE is transitioning from an internal-only prebuilt library to being
built from source in AOSP.

Test: manual, ANGLE.apk's developer options work.
Bug: 142239747

Change-Id: I3e616d6252d0daa0e32c942b05987d17e73a2709