Update eng_fat.c

This line will allow use private keys, which created by Crypto Pro, to
sign with OpenSSL.

CLA: trivial
Reviewed-by: NRich Salz <rsalz@openssl.org>
Reviewed-by: NTim Hudson <tjh@openssl.org>
Reviewed-by: NRichard Levitte <levitte@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/4836)

crypto/engine/eng_fat.c

@@ -108,6 +108,7 @@ int ENGINE_register_complete(ENGINE *e)
 #endif
     ENGINE_register_RAND(e);
     ENGINE_register_pkey_meths(e);
+    ENGINE_register_pkey_asn1_meths(e);
     return 1;
 }