RT2193: #ifdef errors in bss_dgram.c
RT2193: #ifdef errors in bss_dgram.c

Problem with #ifdef in the BIO_CTRL_DGRAM_MTU_DISCOVER case that
is different from the BIO_CTRL_DGRAM_QUERY_MTU one which seems
correct.

Reviewed-by: Matt Caswell <1fa2ef4755a9226cb9a0a4840bd89b158ac71391@openssl.org>

openssl/openssl,openssl/openssl,openssl/openssl,openssl/openssl,openssl/openssl,openssl/openssl