Enable CFI for some media components.

Enables CFI locally for the following components:
   media/libmedia/
   media/libstagefright/codec2/
   media/libstagefright/codecs/aacdec/
   media/libstagefright/codecs/aacenc/
   media/libstagefright/codecs/amrwbenc/
   media/libstagefright/codecs/avc/common/
   media/libstagefright/codecs/avc/enc/
   media/libstagefright/codecs/avcdec/
   media/libstagefright/codecs/avcenc/
   media/libstagefright/codecs/flac/enc/
   media/libstagefright/codecs/g711/dec/
   media/libstagefright/codecs/gsm/dec/
   media/libstagefright/codecs/hevcdec/
   media/libstagefright/codecs/m4v_h263/dec/
   media/libstagefright/codecs/m4v_h263/enc/
   media/libstagefright/codecs/mp3dec/
   media/libstagefright/codecs/mpeg2dec/
   media/libstagefright/codecs/on2/dec/
   media/libstagefright/codecs/on2/enc/
   media/libstagefright/codecs/on2/h264dec/
   media/libstagefright/codecs/opus/dec/
   media/libstagefright/codecs/raw/
   media/libstagefright/http/
   media/libstagefright/httplive/
   media/libstagefright/omx/
   media/libstagefright/wifi-display/

Note that CFI is currently hidden under the global flag,
ENABLE_CFI=true. Unless this is set, local settings are not honored
and CFI will not be enabled. This allows CFI to essentially remain off
on all branches, but will allow it to be tested and debugged using
targeted builds.

Bug: 30227045
Test: m -j40 and device builds and boots
Test: CFI is not enabled unless built with ENABLE_CFI=true
Test: CFI enabled build passes the media CTS tests.