We only need it for MAX_ERRNO, and it's time we had somewhere to put
the little assembler utility macros we've been putting off writing.
Change-Id: I9354d2e0dc47c689296a34b5b229fc9ba75f1a83
Unlike on 32-bit systems where off_t is 32-bit, we don't want to
throw away the top 32 bits of an LP64 system's 64-bit off_t.
Change-Id: Ib2e0daeb4fc0b8ab3d1b983d0b371d8f81033b50