systemctl: fix corrupted output of units

systemctl: fix corrupted output of units

On some systems the list of units in systemctl output came out wrong,
all on one line and with missing descriptions.

It turns out printf() really attempts to mmap 2G memory when INT_MAX is
passed as the field width. On machines with small virtual memory
without overcommit the mmap inside printf() failed.

Do not use INT_MAX for unlimited width.