libFLAC/lpc_intrin_sse41.c: Change usage of _mm_alignr_epi8

Replace
     a = _mm_alignr_epi8(b, a, n);
with
     a = _mm_alignr_epi8(a, b, n);

The resulting code is very slightly faster and the binaries slightly
smaller.

Patch-from: lvqcl <lvqcl.mail@gmail.com>
1 file changed