guile-vm .go files in GUILE_LOAD_PATH

[dsmich]

I've been tracking the guile-vm branch lately and had a recent problem.  After 
much head scratching we finally figured out that a previously installed .go 
file was being used during the buld.

We (Andy and I on irc) hacked around it by creating a new environment variable 
that pre-inst-guile-env can use to override or disable things that libguile 
adds to the load-path.  However, I think there is still a problem.

Basically, a .go file will be preferred over a .scm file even if the .scm file 
is earlier in the load-path.  I think that the file earlier in the load-path 
should win.

Thoughts?

-Dale