Configuring CCLS for CUDA Source Files

[errissa]

I'm struggling to get ccls working with CUDA source files in my project. If I use the compile_commands.json file generated by cmake, ccls seems to fail to index the CUDA source files and diagnostics/auto completion don't work. If I remove compile_commands.json ccls seems to be able to index the CUDA files but there are errors related to global settings.

I reviewed the history on #90 but it's not clear how to use the %cu directive to make the CUDA source indexing work in conjunction with the cmake generated compile_commands.json file. The only way I could make it work was manually removing the CUDA files from compile_commands.json and setting up .ccls manually using %cu. The doesn't seem like it should be necessary.

Any advice is appreciated!