The dep file uses the .rs stem, instead of the .bc stem.

The .bc file stem could be transformed over the source .rs file name by slang.
The build system needs to know the dep file name before slang is run, so we'd like to
take the source .rs file name, which is known before slang is run.

Change-Id: I54c18880582fcc0f177a289b7a6a0f92a5a7806c
3 files changed