[R-SIG-Win] Install multiple versions of Rtools

[Gábor Csárdi]

Hi All,

I would like to have both rtools 3.3 and 3.4 on the same machine, one
in c:\rtools33, the other in c:\rtools34.

I managed to do it via modifying the RHOME/etc/ARCH/Makeconf files. Is
there a better way, by simply setting environment variables?

Thanks much!
Gabor