Since the API has not changed at this point, this is mostly just a
matter of updating Makefiles, and changing references to the library
name in comments.
NetworkManager cannot link to libnm due to the duplicated type/symbol
names. So it links to libnm-core.la directly, which means that
NetworkManager gets a separate copy of that code from libnm.so.
Everything else links to libnm.
Some subdirectories of src/ encapsulate large chunks of functionality,
but src/config/, src/logging/, and src/posix-signals/ are really only
separated out because they used to be built into separate
sub-libraries that were needed either for test programs, or to prevent
circular dependencies. Since this is no longer relevant, simplify
things by moving their files back into the main source directory.
