Revert "cpu: Use xmm1 as a temporary store to make yasm happy building for Mach-O"

This reverts commit b1e7af9e75fe429ea6779c862b721f0700060625.
cpu: Be explicit about size of sha256_init address
Bugfix: Fix build with CPU mining and *without* yasm
Merge branch '20130530_portablecpu' into bfgminer