test/crltest.c: Add check for glue2bio

test/crltest.c: Add check for glue2bio

As the glue2bio() could return NULL pointer if fails,
it should be better to check the return value in order
to avoid the use of NULL pointer.

Signed-off-by: Jiasheng Jiang <jiasheng@iscas.ac.cn>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
Reviewed-by: Paul Dale <pauli@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/17718)