Prefer stdint.h to inttypes.h since the added prototypes form the
latter aren't used. Prefer sys/link_elf.h to link.h so we're only
dependent on the kernel tree. The default installation of link.h just
includes this file, and any benefit from that is outweighed by the
hassle it causes. This reduces the footprint of files needed from the
system includes (or sysroot in buildworld).

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