Since python3 does not use the old print statement, it may not be able
to load gdb-v8-support.py script in gdb as below:

  (gdb) source tools/gdb-v8-support.py
    File "tools/gdb-v8-support.py", line 170
      print result
                 ^
  SyntaxError: Missing parentheses in call to 'print'

This fixes print statement for both python2 and python3.

R=jochen@chromium.org
BUG=

Review-Url: https://codereview.chromium.org/2084163004
Cr-Commit-Position: refs/heads/master@{#37488}