u_char is a nonstandard type. On macOS this requires to explicitly include sys/types.h. Change-Id: I929ceafc12c7cbdcc96e85cdd05cce27d8aa6795
This is to enable binary patching of Hiby-based firmware files Note that noting in rbutil uses this yet. Change-Id: I03ac824dd7402d508eb4e857ad78f184eb0d0243