Merge with Intel ISAL changes from github.com/minio-io/isal

- These changes bring in a much needed Mac OSX port for
    Intel ISAL library
  - At the current stage this MacOSX part of code is
    considered beta
  - pkg/cpu now supports OSX
  - pkg/checksum/crc32c - is still WIP, rest of the packages
    have been validated

pkg/erasure/decode.c

@@ -60,6 +60,8 @@ int32_t minio_get_source_target (int errs, int k, int m,
 
         *source = tmp_source;
         *target = tmp_target;
+
+	return 0;
 }
 
 /*