crypto/conf: gcc build warning fix

crypto/conf: gcc build warning fix

Fix the gcc build warning from conf_sap.c:
variable flags set but not used [-Wunused-but-set-variable]
variable appname set but not used [-Wunused-but-set-variable]
variable filename set but not used [-Wunused-but-set-variable]

CLA: trivial

Signed-off-by: Gang Chen <gang.c.chen@intel.com>
Reviewed-by: Matt Caswell <matt@openssl.org>
Reviewed-by: Paul Dale <pauli@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/20347)