Handle SMIME_crlf_copy return code

Currently the SMIME_crlf_copy result is ignored in all usages. It does
return failure when memory allocation fails.

This patch handles the SMIME_crlf_copy return code in all occurrences.

Signed-off-by: Alon Bar-Lev <alon.barlev@gmail.com>

Reviewed-by: Tomas Mraz <tomas@openssl.org>
Reviewed-by: Paul Dale <pauli@openssl.org>
Reviewed-by: Hugo Landau <hlandau@openssl.org>
(Merged from openssl/openssl#18876)