[PATCH, i386] Fix behavior for –mprefer-vector-width= option

[Shalnov, Sergey]

Hi,
This patch making –mprefer-vector-width= option inclusive. This means that 
if we use –mprefer-vector-width=128 it should switch TARGET_PREFER_AVX128=ON 
and TARGET_PREFER_AVX256=ON also.
It is minor change to generate “xmm” with –mprefer-vector-width=128 
on the platform with “zmm”.

Sergey

2017-11-22  Sergey Shalnov  <sergey.shal...@intel.com>
gcc/
        * config/i386/i386.h (TARGET_PREFER_AVX256): Add inclusiveness of
        the TARGET_PREFER_AVX256 for TARGET_PREFER_AVX128

0006-Fix-behavior-for-mprefer-vector-width-option.patch
Description: 0006-Fix-behavior-for-mprefer-vector-width-option.patch