glog: install pkg-config file

The Autotools build installs a .pc file but the CMake build doesn't,
which causes build failure for e.g. supersonic.

Closes #21800.

Signed-off-by: ilovezfs <ilovezfs@icloud.com>

Formula/glog.rb

@@ -3,7 +3,7 @@ class Glog < Formula
   homepage "https://github.com/google/glog"
   url "https://github.com/google/glog/archive/v0.3.5.tar.gz"
   sha256 "7580e408a2c0b5a89ca214739978ce6ff480b5e7d8d7698a2aa92fadc484d1e0"
-  revision 2
+  revision 3
   head "https://github.com/google/glog.git"
 
   bottle do
@@ -21,6 +21,21 @@ class Glog < Formula
       system "cmake", "..", "-DBUILD_SHARED_LIBS=ON", *std_cmake_args
       system "make", "install"
     end
+
+    # Upstream PR from 30 Aug 2017 "Produce pkg-config file under cmake"
+    # See https://github.com/google/glog/pull/239
+    (lib/"pkgconfig/libglog.pc").write <<~EOS
+      prefix=#{prefix}
+      exec_prefix=${prefix}
+      libdir=${exec_prefix}/lib
+      includedir=${prefix}/include
+
+      Name: libglog
+      Description: Google Log (glog) C++ logging framework
+      Version: #{stable.version}
+      Libs: -L${libdir} -lglog
+      Cflags: -I${includedir}
+    EOS
   end
 
   test do