swr: Align swr_context allocation to SIMD alignment.
swr: Align swr_context allocation to SIMD alignment.

The context now contains SIMD vectors which must be aligned (specifically
samplePositions in the rastState in the derived state).  Failure to align
can result in segv crash on unaligned memory access in vector
instructions.

Reviewed-by: Tim Rowley <54947742fe7299a578dbb84f6c782c6c4c668d8f@intel.com>

metora/MesaGLSLCompiler,metora/MesaGLSLCompiler,metora/MesaGLSLCompiler