replace EVP_MD_CTX_verify() stuff with RSA_verify()/ECDSA_verify()

since the EVP_MD_CTX stuff doesn't seem to exist on osx at all.

tool/util.h

@@ -45,5 +45,7 @@ unsigned char get_algorithm(EVP_PKEY*);
 FILE *open_file(const char*, int);
 int get_object_id(enum enum_slot slot);
 bool set_component_with_len(unsigned char**, const BIGNUM*, int);
+bool prepare_rsa_signature(const unsigned char*, unsigned int, unsigned char*,
+    unsigned int*, int);
 
 #endif