[GTK] fix up the GDB backtrace report tool
https://bugs.webkit.org/show_bug.cgi?id=138564

Reviewed by Carlos Garcia Campos.

* Scripts/webkitpy/port/gtk.py:
(GtkPort._get_crash_log): Match the process name reported by the
driver with the GTK port WebProcess executable filename.
* Scripts/webkitpy/port/linux_get_crash_log.py:
(GDBCrashLogGenerator._get_gdb_output): Invoke gdb for the crashed
program.
(GDBCrashLogGenerator.generate_crash_log): Use %E in the core
pattern to workaround the 16 characters size limit of %e.

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@175867 268f45cc-cd09-0410-ab3c-d52691b4dbfc
webkitpy: demangle C++ symbols from crash log stderr
https://bugs.webkit.org/show_bug.cgi?id=138565

Reviewed by Alexey Proskuryakov.

* Scripts/webkitpy/port/linux_get_crash_log.py:
(GDBCrashLogGenerator.generate_crash_log): Process stderr output
with c++filt.

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@175868 268f45cc-cd09-0410-ab3c-d52691b4dbfc