Source files with more than one . in the name do not get correct object names

As per https://bugreports.qt-project.org/browse/QBS-128 , the baseName function is not appropriate for converting source file names to object file names, because of the ambiguity mentioned there for file names with more than one dot. The fix for that bug adds the completeBaseName function, but at the moment this function is not actually used by the various cpp modules to generate object names!

The changeset at https://codereview.qt-project.org/#change,41255 fixes this problem by using the completeBaseName function to generate object file names from source file names in each of the cpp modules.