Fix regression that caused 'make test' to fail with non-x86 SIMD code.  The round-off error in the SIMD float DCT/IDCT routines only exists in the SSE and SSE2 implementations.


git-svn-id: svn://svn.code.sf.net/p/libjpeg-turbo/code/trunk@1276 632fc199-4ca6-4c93-a231-07263d6284db