FIPS service indicator: Change gcry_get_fips_service_indicator use.

It may return: GPG_ERR_INV_OP, GPG_ERR_NOT_SUPPORTED, or 0.

GPG_ERR_INV_OP: new FIPS service indicator is not implemented
(meaning it's old library).

GPG_ERR_NOT_SUPPORTED: something is non-compliant.

0: it's compliant.

• Signed-off-by: NIIBE Yutaka <gniibe@fsij.org>