RT3497: Clean up "dclean" targets

Some Makefiles had actions for "dclean" that really belonged
to the "clean" target.  This is wrong because clean ends up,
well, not really cleaning everything.

Reviewed-by: Richard Levitte <levitte@openssl.org>
Minor doc fixes.

In EVP_EncryptInit remove duplicate mention of EVP_idea_cbc()
In EVP_PKEY_CTX_ctrl.pod remove EVP_PKEY_get_default_digest_nid
since it is documented elsewhere.

Reviewed-by: Richard Levitte <levitte@openssl.org>