Hard-coded /Developer path in Mac ghc

The Haskell Platform package for Mac OS X installs a /usr/bin/ghc script which hard-codes the path to gcc as:

pgmgcc="/Developer/usr/bin/gcc"

This is incorrect, as Xcode tools can be installed at semi-arbitrary locations, and there may be several versions installed. The correct approach is:

developerpath=`xcode-select --print-path` # Produces "/Developer" or alternative path
pgmgcc="$developerpath/usr/bin/gcc"