Declares a variable that is used only in a
function as a local variable.
Declares a global variable that is used only
in one file as a static global variable.

The static modifier should be used when
the function is used in only one file.

The execution result of `memhog -r6 1G --membind 0 -fmemhog.mmap`
in manuals isn't as expected, it directly use the last assignment
of p, "default", not "membind". We remove the '-' character and
then match it.

`memhog 1G memb` can work, it will cause misunderstanding.
 When the parameter is incorrect, Now it directly use the
last assignment of p, "default".After the fixed, the usage
will be displayed in this case.

`memhog 1G local` will cause crash, because local policy don't
need nodelist, but we still parse nodestring.