Remove printmax_t etc.

Remove printmax_t etc.

printmax_t etc. were needed only for platforms that lacked
support for printing intmax_t.  These platforms are now so
obsolete that they are no longer practical porting targets.
* src/image.c (gs_load): Fix unlikely buffer overrun
discovered while making these changes.  It was introduced in
2011-07-17T00:34:43!eggert@cs.ucla.edu.
* src/lisp.h (printmax_t, uprintmax_t, pMd, pMu, pMx):
Remove.  All uses replaced by their standard counterparts
intmax_t, uintmax_t, PRIdMAX, PRIuMAX, PRIxMAX.