Got rid of some really dead code in the patch.
Ignore some generated files.
Added Building section describing how to build.
Now define the AMIGAOS_BUILTIN_GETLINEARVA as part of the RS6000 builtins.

This hopefully will fix the id clashes.

This is implemented as a separate patch but will be squashed with the
first patch in the next commit.
Squashed patch 1 and 3.

There is no need to change a patch in the same patch set.