SuperOpt

C projects should use C flags rather than CXX flags

1

In CMAKE, the `*CXX*` flags are for C++ only, so C files are not compiled with anything that falls under `CXX` flags. `C` flags should be used for `.c` files.

At least on my OSX system, even with `brew install cairo`, cairo isn't found by the C compiler in the standard locations. Calling `FindPackage` with this FindCairo.cmake script and then...