[RFC/mi] Enable MI by default

[Andrew Cagney]

Hello,

This patch enables MI by default.  I intend committing it in a day or 
so.  I also need to go back through and fix any outstanding problems 
that people reported.

As MichaelC reported, with the MI enabled, there is a slight increase in 
the number of failures.  The ones I've looked at reflected real 
regressions in GDB that occured since the MI testsuite was first 
created.  Even with those failures, I think the MI should be enabled 
now.  As Eli recently pointed out, we've got to check that the MI builds 
on as many platforms as possible.

	Andrew