Add NASM support and stub routine for detecting SIMD extensions.
git-svn-id: svn+ssh://svn.code.sf.net/p/libjpeg-turbo/code/trunk@15 632fc199-4ca6-4c93-a231-07263d6284db
Designed to impose minimal changes on the "normal" code.
git-svn-id: svn+ssh://svn.code.sf.net/p/libjpeg-turbo/code/trunk@14 632fc199-4ca6-4c93-a231-07263d6284db