Static RTS does not build on Linux

[rptb1]

On branch https://github.com/Ravenbrook/mlworks/tree/linux-boot, the runtime system currently fails to link statically with various unresolved symbols in X libraries. The symbols are actually in the libraries, so it might be a link-order problem.

See #2 for a list of prerequisite libraries you need to install.

I have been working on Ubuntu 12 i386, completely vanilla.

In 4799e00 I temporarily hacked the static runtime out of the makefiles so that we can make progress with the boot, but it's inconvenient to set LD_LIBRARY_PATH all the time when developing.