multimedia/x264: switch to _ENABLE option helper
Many opposite switches are not available, so with default options
selected this change incurs the following warnings.
multimedia/libx264: Unknown option --enable-asm, ignored Unknown option --disable-debug, ignored Unknown option --enable-opencl, ignored multimedia/x264: Unknown option --enable-asm, ignored Unknown option --disable-debug, ignored Unknown option --enable-lsmash, ignored
Differential Revision: https://reviews.freebsd.org/D7958
Requested by: koobs (maintainer)