Revert r334090.
It causes the 32bit compat build of libmd to fail with:
libmd/rmd160c.c:86:9: error: 'ripemd160_block' macro redefined
#define ripemd160_block ripemd160_block_x86
^
libmd/ripemd.h:122:9: note: previous definition is here
#define ripemd160_block _libmd_ripemd160_block