Fix build with GMP 5+
https://bugs.php.net/bug.php?id=50990
https://github.com/php/php-src/commit/bd0a74c419f7c81c32ced26c8cd55b9c5cadcea4
--- ext/gmp/gmp.c.orig
+++ ext/gmp/gmp.c
@@ -1380,8 +1380,11 @@ ZEND_FUNCTION(gmp_random)
 
 		GMPG(rand_initialized) = 1;
 	}
+#ifdef GMP_LIMB_BITS
+	mpz_urandomb(*gmpnum_result, GMPG(rand_state), GMP_ABS (limiter) * GMP_LIMB_BITS);
+#else
 	mpz_urandomb(*gmpnum_result, GMPG(rand_state), GMP_ABS (limiter) * __GMP_BITS_PER_MP_LIMB);
-
+#endif
 	ZEND_REGISTER_RESOURCE(return_value, gmpnum_result, le_gmp);
 }
 /* }}} */