Merge commit '57b753b4'

* commit '57b753b4':
  build: Prefer NASM assembler over YASM
  build: Make x86 assembler commandline-selectable
  build: Special-case handling of SDL CFLAGS

This commit is a noop, see
fde3bb16
3cc73d3d
4f9297acMerged-by: James Almer <jamrial@gmail.com>