pkg-config for compilation/linking arguments

[keynmol]

Closes #18
Closes #4

Very basic/hacky integration with pkg-config.

The main goal is to rely on package's own understanding of what it needs to compile/link. With changes in this PR even for a library as huge as GTK, your nativeConfig definition can look like this:

vcpkgDependencies := Set("gtk")

nativeConfig := {
  val conf = nativeConfig.value
  val pkgConfig = vcpkgConfigurator.value

  conf
    .withCompileOptions(
      pkgConfig.updateCompilationFlags(conf.compileOptions, "gtk4")
    )
    .withLinkingOptions(
      pkgConfig.updateLinkingFlags(conf.linkingOptions, "gtk4")
    )
}

And yes, of course gtk4 is different from vcpkg's package name.

And for binding builder:

import bindgen.interface.Binding

bindgenBindings := {
  val manager = vcpkgManager.value
  val pkgConfig = vcpkgConfigurator.value
  Seq(
    Binding(
      manager.includes("gtk") / "gtk-4.0" / "gtk" / "gtk.h",
      "gtk",
      cImports = List("gtk/gtk.h"),
      clangFlags = pkgConfig.compilationFlags("gtk4").toList
    )
  )
}

Unfortunately binding generator breaks on GTK about halfway through, but the flags passed in are sufficient for clang to parse the entire file.

In comparison, here's what you had to manually add to attempt to compile gtk:

def allTheFuckingIncludes(manager: com.indoorvivants.vcpkg.Vcpkg) = {
  val gtk = manager.includes("gtk") / "gtk-4.0"
  val glib = manager.includes("glib") / "glib-2.0"
  val cairo = manager.includes("cairo") / "cairo"
  val glibOther = manager.files("glib").libDir / "glib-2.0" / "include"

  List(
    gtk,
    glib,
    glibOther,
    cairo,
    manager.includes("pango") / "pango-1.0",
    manager.includes("harfbuzz") / "harfbuzz",
    manager.includes("gdk-pixbuf") / "gdk-pixbuf-2.0",
    manager.includes("graphene") / "graphene-1.0",
    manager.files("graphene").libDir / "graphene-1.0" / "include"
  )
    .map(_.toString)
    .map("-I" + _)
}