Remove CFI diagnostics.

Remove diagnostics mode from CFI across the board. This should reduce
performance overhead and also allows the minimal runtime to work when
other ubsan sanitizers are enabled. CFI stack dumps should include a
CFI related function, so it should be apparent when a crash is
CFI-related.

Bug: 117417735
Test: make -j
Change-Id: Ie697f83b4894230ac90a4de447dccbc006c9c5a6