Two changes:

Two changes:
- Be more robust in the face of malformed stack traces.  This avoids some
  potential assertion errors (which have affected prior versions of Massif),
  but unfortunately reduces the amount of sanity-checking that can be done
  on XTrees.

- Get white-space printing right in output file.  Non-functional change,
  just makes output files easier to read.

git-svn-id: svn://svn.valgrind.org/valgrind/trunk@7270