Makefile now builds using cabal, taking advantage of cabal's automatic detection of appropriate build flags.

The only thing lost is ./ghci

Speed: make fast used to take 20 seconds here, when rebuilding from
touching Command/Unused.hs. With cabal, it's 29 seconds.

Utility/Shell.hs

@@ -10,7 +10,7 @@
 module Utility.Shell where
 
 shellPath :: FilePath
-#ifndef WITH_ANDROID
+#ifndef __ANDROID__
 shellPath = "/bin/sh"
 #else
 shellPath = "/system/bin/sh"