bug#7213: [PATCH] sort: fix buffer overrun on 32-bit hosts when warning re obsolete...

bug#7213: [PATCH] sort: fix buffer overrun on 32-bit hosts when warning re obsolete keys

* src/sort.c (key_warnings): Local buffer should be of size
INT_BUFSIZE_BOUND (uintmax_t), not INT_BUFSIZE_BOUND (sword).
This bug was discovered by running 'make check' on a 32-bit
Solaris 8 sparc host, using Sun cc.  I saw several other instances
of invoking umaxtostr on a buffer declared to be of size
INT_BUFSIZE_BOUND (VAR), and these instances should at some point
be replaced by INT_BUFSIZE_BOUND (uintmax_t) too, as that's a
less error-prone style.