Add formulas to build keg-only libepoxy

Formula/libepoxy@20211103.1.rb

@@ -0,0 +1,57 @@
+class LibepoxyAT202111031 < Formula
+  desc "Library for handling OpenGL function pointer management"
+  homepage "https://github.com/anholt/libepoxy"
+  url "https://code.tokarch.uk/third_party/libepoxy.git", using: :git, revision: "2b69a68ae3f6a3f63fe6166677fa8e8b15471c1b"
+  version "20211103.1"
+  license "MIT"
+
+  depends_on "meson" => :build
+  depends_on "ninja" => :build
+  depends_on "pkg-config" => :build
+  depends_on "python@3.9" => :build
+
+  depends_on "libangle"
+
+  keg_only :versioned_formula
+
+  def install
+    mkdir "build" do
+      system "meson", *std_meson_args, 
+             "-Dc_args=-I#{Formula["libangle"].opt_prefix}/include",
+             "-Dc_link_args=-L#{Formula["libangle"].opt_prefix}/lib",
+             "-Degl=yes", "-Dx11=false",
+             ".."
+      system "ninja", "-v"
+      system "ninja", "install", "-v"
+    end
+  end
+
+  test do
+    (testpath/"test.c").write <<~EOS
+
+      #include <epoxy/gl.h>
+      #include <OpenGL/CGLContext.h>
+      #include <OpenGL/CGLTypes.h>
+      #include <OpenGL/OpenGL.h>
+      int main()
+      {
+          CGLPixelFormatAttribute attribs[] = {0};
+          CGLPixelFormatObj pix;
+          int npix;
+          CGLContextObj ctx;
+
+          CGLChoosePixelFormat( attribs, &pix, &npix );
+          CGLCreateContext(pix, (void*)0, &ctx);
+
+          glClear(GL_COLOR_BUFFER_BIT);
+          CGLReleasePixelFormat(pix);
+          CGLReleaseContext(pix);
+          return 0;
+      }
+    EOS
+    system ENV.cc, "test.c", "-L#{lib}", "-lepoxy", "-framework", "OpenGL", "-o", "test"
+    system "ls", "-lh", "test"
+    system "file", "test"
+    system "./test"
+  end
+end

Formula/libepoxy@20220315.1.rb

@@ -0,0 +1,57 @@
+class LibepoxyAT202203151 < Formula
+  desc "Library for handling OpenGL function pointer management"
+  homepage "https://github.com/anholt/libepoxy"
+  url "https://code.tokarch.uk/third_party/libepoxy.git", using: :git, revision: "001a36c01a66c0171758ef1a3709019d03391158"
+  version "20220315.1"
+  license "MIT"
+
+  depends_on "meson" => :build
+  depends_on "ninja" => :build
+  depends_on "pkg-config" => :build
+  depends_on "python@3.9" => :build
+
+  depends_on "libangle"
+
+  keg_only :versioned_formula
+
+  def install
+    mkdir "build" do
+      system "meson", *std_meson_args,
+             "-Dc_args=-I#{Formula["libangle"].opt_prefix}/include",
+             "-Dc_link_args=-L#{Formula["libangle"].opt_prefix}/lib",
+             "-Degl=yes", "-Dx11=false",
+             ".."
+      system "ninja", "-v"
+      system "ninja", "install", "-v"
+    end
+  end
+
+  test do
+    (testpath/"test.c").write <<~EOS
+
+      #include <epoxy/gl.h>
+      #include <OpenGL/CGLContext.h>
+      #include <OpenGL/CGLTypes.h>
+      #include <OpenGL/OpenGL.h>
+      int main()
+      {
+          CGLPixelFormatAttribute attribs[] = {0};
+          CGLPixelFormatObj pix;
+          int npix;
+          CGLContextObj ctx;
+
+          CGLChoosePixelFormat( attribs, &pix, &npix );
+          CGLCreateContext(pix, (void*)0, &ctx);
+
+          glClear(GL_COLOR_BUFFER_BIT);
+          CGLReleasePixelFormat(pix);
+          CGLReleaseContext(pix);
+          return 0;
+      }
+    EOS
+    system ENV.cc, "test.c", "-L#{lib}", "-lepoxy", "-framework", "OpenGL", "-o", "test"
+    system "ls", "-lh", "test"
+    system "file", "test"
+    system "./test"
+  end
+end