LibGUI remove DEBUG

DEBUG_ONLY_CODE flag enables expensive checks such as
BufferQueueCore::validateConsistencyLocked() which when running
represents 15.1% of SurfaceFlinger total runtime. Enabling these
check for "eng" build only make "userdebug" build closer to "user".

Test: Manual
Bug: 62905241
Change-Id: I77065ecf4e62261c3f02b1cad9966d5c4845c639
1 file changed