Revert "json-c 0.11"

Apparently the shared library has been split into two libraries on 0.11,
which breaks things that are dependent on the old structure (e.g.
postgis).

See Homebrew/homebrew#19068.

This reverts commit a37b4561a6f1664888568ad4c0c44e44d38bee18.

Formula/json-c.rb

@@ -2,15 +2,16 @@ require 'formula'
 
 class JsonC < Formula
   homepage 'https://github.com/json-c/json-c/wiki'
-  url 'https://github.com/json-c/json-c/archive/json-c-0.11-20130402.tar.gz'
-  version '0.11'
-  sha1 '1910e10ea57a743ec576688700df4a0cabbe64ba'
+  url 'https://github.com/downloads/json-c/json-c/json-c-0.10.tar.gz'
+  sha1 'f90f643c8455da21d57b3e8866868a944a93c596'
 
   def install
     system "./configure", "--disable-dependency-tracking",
                           "--prefix=#{prefix}"
-
-    ENV.deparallelize
     system "make install"
+
+    # The Makefile forgets to install this header. This is fixed upstream and
+    # can be pulled on the next release.
+    (include/'json').install 'json_object_iterator.h'
   end
 end