Disable use of assembly on MIPS to allow it to build. MIPS is not
expected to be high performance in OpenWrt, and this allows it to still
be used for media identification as updated versions of ffmpeg are
brought in.
The error is in
libavcodec/mips/aacdec_mips.c: In function 'imdct_and_windowing_mips'
regarding: 'asm' has impossible constraints in multiple locations.
Signed-off-by: Ian Leonard <antonlacon@gmail.com>