LC_REQ_DYLD
#define LC_LOAD_WEAK_DYLIB (0x18 | LC_REQ_DYLD)
#define LC_RPATH (0x1c | LC_REQ_DYLD) /* runpath additions */
#define LC_REEXPORT_DYLIB (0x1f | LC_REQ_DYLD) /* load and re-export dylib */
#define LC_DYLD_INFO_ONLY (0x22|LC_REQ_DYLD) /* compressed dyld information only */
#define LC_LOAD_UPWARD_DYLIB (0x23 | LC_REQ_DYLD) /* load upward dylib */
#define LC_MAIN (0x28|LC_REQ_DYLD) /* replacement for LC_UNIXTHREAD */