Minor. Fixing storing of gdb binary paths in profile.xml

* keeps paths in form of C:/.../.../... on windows
* instead of C:\..\..\..\

Change-Id: I5d645ab136c92fbdd5f9750265213ba974fac38a
Reviewed-by: Tobias Hunger <tobias.hunger@digia.com>
CppTools: Tests: Refactor / Clean up cppcompletion_test.cpp

* Open the files in the cpp editor, so preprocessing will take place
* Remove duplicated code
* Fix coding styles issues

Change-Id: Ic8bffcbc5a4ac5aca76bc55880d33c3b55f0944c
Reviewed-by: Fawzi Mohamed <fawzi.mohamed@digia.com>