capi_cert_get_fname: check for NULL after allocating wfname
capi_cert_get_fname: check for NULL after allocating wfname

Signed-off-by: Kurt Roeckx <bb87b47479d83cec3c76132206933257ded727b2@roeckx.be>
Reviewed-by: Richard Levitte <5fb523282dd7956571c80524edc2dccfa0bd8234@openssl.org>

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