posix-xprintf-functions.patch from patch #6230.

Add fprintf-posix, printf-posix, printf-safe,
snprintf-posix, sprintf-posix, vasprintf-posxi, vfprintf-posix,
vprintf-posix, vsnprintf-posix, and vsprintf-posix modules, which
allow us to use C99 format specifiers (e.g. 'z') in *printf.
Also, changed many formerly casted arguments in *printf calls to
use one of these format specifiers and drop the cast.