Icecast: Include src/*/test*.c once 3C can handle multiple mains

[mattmccutchen-cci]

From #13 (review):

It looks like this is skipping the test.c files (which contain duplicate mains) without an explicit --skip flag. This behavior is fine for now since the duplicate mains would cause 3c to raise an error, but we will probably want to include them when correctcomputation/checkedc-clang#505 is merged.

The reason these files are not being included now appears to be that they are not built by the default ./configure && make, so Bear doesn't add them to the compilation database. We'd have to figure out the correct arguments to ./configure and/or make to build the files.