C++: clean-up CppCompletionAssist.

This is step 1 of 2 for merging the various provider factories into a
single class. Merging has the advantage that selecting based on editor
(content) mime-type only has to select one class, instead of re-doing
the selection for each class separately.

Change-Id: I11f815151bd4769ae6028b636793d6a80d02e202
Reviewed-by: Nikolai Kosjar <nikolai.kosjar@digia.com>
Add qbs project file for valgrind-fake.

Change-Id: I14d1b0e04650ef9c717be3f5ca2d7eab1017cd77
Reviewed-by: Joerg Bornemann <joerg.bornemann@digia.com>
qbs project files: Add project property ide_source_tree.

The qmake project has this as well. Will become more useful later on.

Change-Id: I6e9b6b1d1a46ea6263a6d5fac4cb30d883a3e077
Reviewed-by: Joerg Bornemann <joerg.bornemann@digia.com>