Remove the !SSLASM conditional. Either there is an arch-specific Makefile.inc,
or the !SSLASM list of files applies. This allows for an arch-specific
Makefile.inc to not specify SSLASM.
Enable the assembler code for BN, which was lost quite some time ago.
Enable assembler code for DES. Assembler code for BN is commented out as it
uses the `umul' and `udiv' instructions directly, which are not supported
on v7 processors.