arm: Add an option for making sure NEON registers aren't clobbered

This is pretty much based on the same test for XMM registers.

Signed-off-by: Martin Storsjö <martin@martin.st>
Merge remote-tracking branch 'qatar/master'

* qatar/master:
  arm: Add an option for making sure NEON registers aren't clobbered

Conflicts:
	configure

Merged-by: Michael Niedermayer <michaelni@gmx.at>
avcodec/alac: only set *got_frame_ptr when all channels have been decoded

Fixes use of uninitialized memory
Fixes: msan_uninit-mem_7f8b64436530_7895_quicktime_newcodec_applelosslessaudiocodec.m4a
Found-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>