glog: gflags compatibility fix

Closes Homebrew/homebrew#34416. The upstream issue tracker for Glog is pretty dead, and
gflags development seems to be outpacing it considerably, so vendoring
the old version of gflags is a workaround.

Closes Homebrew/homebrew#34451.

Signed-off-by: Mike McQuaid <mike@mikemcquaid.com>

Formula/glog.rb

@@ -1,11 +1,15 @@
-require 'formula'
+require "formula"
 
 class Glog < Formula
-  homepage 'http://code.google.com/p/google-glog/'
-  url 'https://google-glog.googlecode.com/files/glog-0.3.3.tar.gz'
-  sha1 'ed40c26ecffc5ad47c618684415799ebaaa30d65'
+  homepage "https://code.google.com/p/google-glog/"
+  url "https://google-glog.googlecode.com/files/glog-0.3.3.tar.gz"
+  sha1 "ed40c26ecffc5ad47c618684415799ebaaa30d65"
 
-  depends_on 'gflags'
+  # Vendor an older version of gflags as the new version makes compile = nope.
+  resource "gflags" do
+    url "https://gflags.googlecode.com/files/gflags-2.0.tar.gz"
+    sha1 "dfb0add1b59433308749875ac42796c41e824908"
+  end
 
   if MacOS.version >= :mavericks
     # Since 0.3.4 has not yet been released, manually apply
@@ -24,8 +28,22 @@ class Glog < Formula
   end
 
   def install
+    resource("gflags").stage do
+      system "./configure", "--disable-dependency-tracking", "--prefix=#{libexec}/gflags"
+      system "make", "install"
+    end
+
+    # Find our sandboxed gflags.
+    ENV.append_to_cflags "-I#{libexec}/gflags/include"
+    ENV.append "LDFLAGS", "-L#{libexec}/gflags/lib"
+
     system "./configure", "--disable-dependency-tracking",
                           "--prefix=#{prefix}"
-    system "make install"
+    system "make", "install"
+  end
+
+  test do
+    assert_equal "#{libexec}/gflags/lib/libgflags.2.dylib (compatibility version 4.0.0, current version 4.0.0)",
+    shell_output("otool -L #{lib}/libglog.0.dylib | grep libgflags").strip
   end
 end