Test program with C and C++ sources

[langston-barrett]

We've been testing MATE on codebases that are either C++ or C, but many real-world codebases are both. We should confirm that, particularly on the machine code mapping side, having multiple compilation units of different origin languages doesn't cause problems.

The recompilation pipeline inside of quotidian needs to know how best to recompile the assembly it's given. It currently deduces the right compiler frontend to use (clang or clang++) based on the DWARF language ID(s) for each compilation unit, which aren't guaranteed to all be the same.

Migrated from internal (Gitlab) MATE issue number(s) 440.