Show providers as dependencies of virtual packages in dotty-build
Merge pull request #67 from bcully/master

Add providers as dependencies of virtual packages
filter out providers with same name as providee to make dotty-build a DAG again
Merge pull request #68 from bcully/master

filter out providers with same name as providee
Add compiler_wrapper for clang and clang++ on 10.6

Some packages now look for "clang" by name, which evades fink's
single-arch wrapper tricks.