PATCH RFA: Remove prev-DIR/Makefile to force reconfigure

[Paolo Bonzini]

Ian Lance Taylor wrote:
> There is code in the top level configure.in file to force
> subdirectories to be reconfigured by removing DIR/Makefile.  That code
> handles stage*-DIR.  However, if you have completed a bootstrap, the
> directories will be named stage1-DIR and prev-DIR.  In order to
> properly force a reconfigure, prev-DIR/Makefile needs to be removed
> also.
> 
> This patch does that.  Tested by running configure.  OK for mainline?
> I will commit to src after approved for gcc.

It makes a lot of sense to me at least.

Paolo