[polyml] suppressing compiler output

I've added a "polyc" script that is generated from the build process. The idea of this is to provide the similar sort of functionality that users of C expect from the "cc" command. It's very simple at the moment and is limited to a few options. It compiles an ML source file and exports the "main" function. The -o option specifies where the executable is to be placed, defaulting to a.out on Unix.

david@dunedin:~$ cat hello.ML fun main() = print "Hello World\n"; david@dunedin:~$ polyc hello.ML -o hello david@dunedin:~$ ./hello Hello World

The script includes the path names to where the poly binary and the libraries will be installed so it's not possible to run it within the build directory. David