build: use more gnulib modules for better POSIX compliance

build: use more gnulib modules for better POSIX compliance

* bootstrap.conf (gnulib_modules): Add modules exposed via
make CFLAGS=-DGNULIB_POSIXCHECK 2>&1 \
|perl -lne '/.* use gnulib module (\S+).*/ and print $1' \
|sort |uniq -c|sort -nr
Add these: calloc close fclose fprintf-posix lstat malloc
perror printf-posix realloc