WOLFSSL_PUBLIC_MP and disable algorithms didn't work because of api.c.
- mp_cond_copy not available unless ECC compiled in
- wc_export_int not available unless ECC compiled in
Enabling only DH and using SP with SP Math didn't work as the DH
parameters were too small.
sp_cmp is needed when only DH.
mp_set_int is was not available in SP math when RSA is not defined.
mp_set is close enough for the use cases.
Configure with SP and SP math but not RSA, DH and ECC didn't configure -
now default to small maths.
5a72fee3df