Add pkg-config shim for libplist in libgpod formula to ensure compatibility with Homebrew's library naming conventions during installation.

Formula/libgpod.rb

@@ -19,6 +19,25 @@ class Libgpod < Formula
   depends_on "sqlite"
 
   def install
+    # libgpod's configure.ac checks for pkg-config module name "libplist".
+    # Homebrew provides "libplist-2.0", so we provide a tiny shim .pc file to
+    # satisfy the expected name.
+    (buildpath/"brew-pkgconfig").mkpath
+    (buildpath/"brew-pkgconfig/libplist.pc").write <<~EOS
+      prefix=#{Formula["libplist"].opt_prefix}
+      exec_prefix=${prefix}
+      libdir=#{Formula["libplist"].opt_lib}
+      includedir=#{Formula["libplist"].opt_include}
+
+      Name: libplist
+      Description: Apple property list library (Homebrew shim for libgpod)
+      Version: #{Formula["libplist"].version}
+      Libs: -L${libdir} -lplist-2.0
+      Cflags: -I${includedir}
+    EOS
+
+    ENV.prepend_path "PKG_CONFIG_PATH", buildpath/"brew-pkgconfig"
+
     # Ensure pkg-config can find Homebrew keg .pc files during configure.
     ENV.prepend_path "PKG_CONFIG_PATH", Formula["libplist"].opt_lib/"pkgconfig"
     ENV.prepend_path "PKG_CONFIG_PATH", Formula["sqlite"].opt_lib/"pkgconfig"