We have been checking the mawk version by extracting <x>, <y>, <z>,
and <d> part from "mawk <x>.<y>.<z> <d>" in the output of the "mawk -W
version" and testing <x>, <y>, <z>, and <d> using an arithmetic
evalaution. However, <d> is ensured to be an integer only in "x.y.z
>= 1.3.4". Otherwise, it may cause a syntax error in the arithmetic
evaluation. The mawk started to include the date as an integer in the
<d> position only from mawk-1.3.3-20090721. We should first check
that "x.y.z >= 1.3.4" and then check the value of "d". In case, "mawk
-W version" produces a completely different text, we should also
redirect stderr of the arithmetic commands to /dev/null.
