checkmk: change POSIX bracket expressions to be compatible with GNU/Hurd
checkmk: change POSIX bracket expressions to be compatible with GNU/Hurd

The version of mawk included in Hurd is quite old (at least 8 years)
and did not support the bracket extensions previously used.

tarruda/check,tarruda/check,tarruda/check,tarruda/check,tarruda/check