If there is a .wdl file with the name of the .c file it will be compiled first. This was needed to set things like the plugindir. Just look at the betapage for the PRAGMA_ defines which now replace the need for a .wdl file.
Other than that you can combine C-Script and Lite-C, but that is a bit different because the function main has to be in the .wdl file and you just include the .c file as any other script. That one needs a startup function which works as function main for the lite-c part because it is not possible to share functions or variables or such between them. But that allows for example to use the new postprocessing features in a c-script project.

And I was again too late :P