Do not collect source files via globbing

[90degs2infty]

Currently, the project's source files are collected via globbing. src/libdbcppp/CMakeLists.txt is one example (see lines 31ff), but this certainly applies to other CMakeLists.txt as well.

The docs explicitly discourage this way of collecting sources:

We do not recommend using GLOB to collect a list of source files from your source tree.

-- reference

Instead, consider listing the sources explicitly.