pmap: fixing broken indentation in the -X/-XX modes

pmap: fixing broken indentation in the -X/-XX modes

This commit changes the processing principle of the -X/-XX modes
from 1-pass to 2-pass. A separate width measurement stage has been
added, so that the real maximum widths can be measured and used
for correct indentation.

The firstmapping variable now has a new value (2) used for the
width measurement stage (1st pass). The printing is disabled
in this stage. The file position is reset to the beginning
of the file once the end of file is reached and the printing stage
(2nd pass) begins.
It's questionable if this approach is sensitive to Read-after-Write
race conditions. Anyway, this feature is a good candidate for
a complete redesign in the future.

Additionally this commit introduces a final cleaning of the list
used for the evaluation of totals in the -X/-XX modes.