CodeBlocks: Show generated files in non-utility targets

Since 2.6.3 the UTILITY target may have source files. A defect was filed
that these files are now visible in the source tree. A fix later removed
all generated files from the source tree, regardless of the target type.
You can't even include them by using the SOURCES option. This fix adds
generated files again, except for the UTILITY target which cluttered the
source tree.

Fixes #14272.