log4cxx: darwin compatibility

This patch replicates the patch logic from the brew recipe
<56b57d583e/Library/Formula/log4cxx.rb>
which is necessary to build on darwin.

pkgs/development/libraries/log4cxx/default.nix

@@ -20,6 +20,9 @@ stdenv.mkDerivation rec {
     }' src/examples/cpp/console.cpp \
        src/main/cpp/inputstreamreader.cpp \
        src/main/cpp/socketoutputstream.cpp
+  '' + stdenv.lib.optionalString stdenv.isDarwin ''
+  sed -i 's/namespace std { class locale; }/#include <locale>/' src/main/include/log4cxx/helpers/simpledateformat.h
+  sed -i 's/\(#include <cctype>\)/\1\n#include <cstdlib>/' src/main/cpp/stringhelper.cpp
   '';
 
   buildInputs = [autoconf automake libtool libxml2 cppunit boost apr aprutil db expat];