mk files .../*/*.rs regexp does not go deep enough

[pnkfelix]

A quick note of something I observed before I head out:

Modifying src/librustc/middle/typeck/check/regionmanip.rs, then running make in my build dir, make did not see that it had to do a rebuild.

I had to touch src/librustc/middle/typeck/mod.rs before make would proceed to rebuild rustc.

This is probably just a matter of replacing one of the series of *.rs */*.rs */*/*.rs ... regexp with an extra entry or two on the end.

[alexcrichton]

The relevant lines in the makefile are here: https://github.com/mozilla/rust/blob/master/mk/crates.mk#L108-L109

[edwardw]

We have a recursive wildcard function: mk/reconfig.mk#L11