Cleanup C and C++ compiler flags

Cleanup C and C++ compiler flags

Cleanup the setting of C and C++ compiler flags:
 * (Almost) all compiler flags are set uniformly
   in the system/bt/Android.mk file.
 * Enable by default breaking the compilation if there is a
   compilation warning: -Werror
 * Enable most compilation warnings: -Wall -Wextra
 * Renamed Android.mk related flags:
   - bdroid_C_INCLUDES -> bluetooth_C_INCLUDES
   - bdroid_CFLAGS -> bluetooth_CFLAGS
 * Introduce variables for C-only and C++ only compiler:
   - bluetooth_CFLAGS: common C and C++ compiler flags
   - bluetooth_CONLYFLAGS: C only compiler flags
   - bluetooth_CPPFLAGS: C++ only compiler flags
 * Disable warnings for existing issues - to be removed as issues are
   resolved
 * Add a workaround for libchrome and -DNDEBUG usage.

Bug: 26879229
Change-Id: Ie7595965ca0c8ead0e95e983e76c327e7891b2c3