Add formulas to build keg-only virgl libraries

Formula/virglrenderer@20211103.1.rb

@@ -0,0 +1,31 @@
+class VirglrendererAT202111031 < Formula
+  desc "VirGL virtual OpenGL renderer"
+  homepage "https://gitlab.freedesktop.org/virgl/virglrenderer"
+  url "https://code.tokarch.uk/third_party/virglrenderer.git", revision: "754a303015ef082f9c0da48a67398ad376191964"
+  version "20211103.1"
+  license "MIT"
+
+  depends_on "meson" => :build
+  depends_on "ninja" => :build
+  depends_on "pkg-config" => :build
+
+  depends_on "libangle"
+  depends_on "libepoxy@20211103.1"
+
+  keg_only :versioned_formulae
+
+  def install
+    mkdir "build" do
+      system "meson", *std_meson_args,
+             "-Dc_args=-I#{Formula["libepoxy@20211103.1"].opt_prefix}/include -I#{Formula["libangle"].opt_prefix}/include",
+             "-Dc_link_args=-L#{Formula["libepoxy@20211103.1"].opt_prefix}/lib -L#{Formula["libangle"].opt_prefix}/lib",
+             ".."
+      system "ninja", "-v"
+      system "ninja", "install", "-v"
+    end
+  end
+
+  test do
+    system "true"
+  end
+end

Formula/virglrenderer@20220315.1.rb

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+class VirglrendererAT202203151 < Formula
+  desc "VirGL virtual OpenGL renderer"
+  homepage "https://gitlab.freedesktop.org/virgl/virglrenderer"
+  url "https://code.tokarch.uk/third_party/virglrenderer.git", revision: "c8b112f5f530f80eb6dbf6578354433a6a3eaa2b"
+  version "20220315.1"
+  license "MIT"
+
+  depends_on "meson" => :build
+  depends_on "ninja" => :build
+  depends_on "pkg-config" => :build
+
+  depends_on "libangle"
+  depends_on "libepoxy@20220315.1"
+
+  keg_only :versioned_formulae
+
+  def install
+    mkdir "build" do
+      system "meson", *std_meson_args,
+              "-Dc_args=-I#{Formula["libepoxy@20220315.1"].opt_prefix}/include -I#{Formula["libangle"].opt_prefix}/include",
+              "-Dc_link_args=-L#{Formula["libepoxy@20220315.1"].opt_prefix}/lib -L#{Formula["libangle"].opt_prefix}/lib",
+              ".."
+      system "ninja", "-v"
+      system "ninja", "install", "-v"
+    end
+  end
+
+  test do
+    system "true"
+  end
+end
+  
+