[Linaro-uefi] [inputs required]: build system improvement

Hi guys,

There was some complaints about shortcomings of EDK2 build system, like "make clean" doesn't work correct, dependency checking is lame, etc. It would be really great to collect here all inputs with explanations (or steps how to reproduce). So if you happened to notice that something is wrong with EDK2 build system -- please provide this information here. I also don't really understand what is wrong with clean scripts and dependency checking (just heard complaints without explanations), so if you know any details -- please provide it here as well.

Once I have enough inputs I will solicit feedback from the community and will try to upstream fixes.

Thanks!