Add the possibility to build without the ENGINE framework.

PR: 287

crypto/dsa/dsa_ossl.c

@@ -64,7 +64,9 @@
 #include <openssl/dsa.h>
 #include <openssl/rand.h>
 #include <openssl/asn1.h>
+#ifndef OPENSSL_NO_ENGINE
 #include <openssl/engine.h>
+#endif
 
 static DSA_SIG *dsa_do_sign(const unsigned char *dgst, int dlen, DSA *dsa);
 static int dsa_sign_setup(DSA *dsa, BN_CTX *ctx_in, BIGNUM **kinvp, BIGNUM **rp);