Get darwinbuild working.

- see http://darwinbuild.macosforge.org/trac/ticket/109, must use xcodebuild instead of make, at least on snow leopard
- xcode seems to use cc even for c++ files, which doesn't work, so just removing CC and LD from the environment

Signed-off-by: Adam Vandenberg <flangy@gmail.com>

Formula/darwinbuild.rb

@@ -9,8 +9,9 @@ class Darwinbuild <Formula
   end
 
   def install
-    ENV.no_optimization
+    ENV.delete('CC')
-    system "make install PREFIX=#{prefix}"
+    ENV.delete('LD')
+    system "xcodebuild -configuration Release install DSTROOT=/ PREFIX=#{prefix}"
   end
 end