Revert "lmdb: add pkg-config file (#12950)" (#13626)

This reverts commit 9d554c7019.

Formula/lmdb.rb

@@ -20,22 +20,6 @@ class Lmdb < Formula
       system "make", "test", "SOEXT=.dylib"
       system "make", "install", "SOEXT=.dylib", "prefix=#{prefix}"
     end
-    (lib/"pkgconfig/lmdb.pc").write(lmdb_pc)
-  end
-
-  def lmdb_pc; <<-EOS.undent
-    prefix=#{prefix}
-    exec_prefix=#{prefix}
-    libdir=${exec_prefix}/lib
-    includedir=${prefix}/include
-
-    Name: liblmdb
-    Description: Lightning Memory-Mapped Database
-    URL: https://symas.com/products/lightning-memory-mapped-database/
-    Version: #{version}
-    Libs: -L${libdir} -llmdb
-    Cflags: -I${includedir}
-    EOS
   end
 
   test do