When exconf.rb cannot create_makefile for some reason (e.g., a platform 
issue), install.rb still tries to execute the make program in that dir. 
The make program fails, finding no makefile, and install.rb reports that 
as an error.

Is there some way to avoid this being reported as an error? ATM, I just 
print out a message (from my extconf.rb) saying "please ignore the error 
message after running 'install.rb setup'", but that's not very user 
friendly...