engine: remove constants for ENGINE_METHOD_BN_MOD_EXP{,_CRT}

These macros do not exist in OpenSSL 0.9.7 or later, which was released
in 2002.

Author: rhenium

ext/openssl/ossl_engine.c

@@ -549,12 +549,6 @@ Init_ossl_engine(void)
     DefEngineConst(METHOD_DSA);
     DefEngineConst(METHOD_DH);
     DefEngineConst(METHOD_RAND);
-#ifdef ENGINE_METHOD_BN_MOD_EXP
-    DefEngineConst(METHOD_BN_MOD_EXP);
-#endif
-#ifdef ENGINE_METHOD_BN_MOD_EXP_CRT
-    DefEngineConst(METHOD_BN_MOD_EXP_CRT);
-#endif
     DefEngineConst(METHOD_CIPHERS);
     DefEngineConst(METHOD_DIGESTS);
     DefEngineConst(METHOD_ALL);