Target specific sources

[pedrolamarao]

Provide DSL for configuring target specific sources.
It is enough to allow including sources by pattern.

[pedrolamarao]

Do we really need more than this?

tasks.named<MetalCompileTask>("compile-main-cxx") {
    when (target.get()) {
        "i686-elf" -> include("x86_32-elf/*")
        "x86_64-elf" -> include("x86_64-elf/*")
    }
}

[pedrolamarao]

Yes, we do: we must apply the same include/exclude patterns to both compile objects and compile commands tasks.