ssl/t1_lib.c: Add checks for the EVP_MD_get_size()

ssl/t1_lib.c: Add checks for the EVP_MD_get_size()

Add checks for the EVP_MD_get_size() to avoid unexpected negative numbers.

Fixes: b362ccab5c ("Security framework.")
Fixes: 0fe3db251a ("Use size of server key when selecting signature algorithm.")
Signed-off-by: Jiasheng Jiang <jiasheng@purdue.edu>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
Reviewed-by: Neil Horman <nhorman@openssl.org>
Reviewed-by: Tom Cosgrove <tom.cosgrove@arm.com>
(Merged from https://github.com/openssl/openssl/pull/23943)