Relocate GCC with a single environment var (/win32 reg) for 2.8.0?

[Mumit Khan]

According to NEWS: 

  You can now relocate all GCC files with a single environment variable
  or a registry entry under Windows 95 and Windows NT.

This is yet to be documented in the info files, and I have yet to decipher
how exactly the new code in gcc.c and prefix.c works. Could somebody
please enlightmen me?

Thanks
Mumit -- khan@xraylith.wisc.edu
http://www.xraylith.wisc.edu/~khan/