Revert "go/buildutil: handle symlinks in filenames"

Reason: ContainingPackage should do all I/O through build.Context.

This reverts commit 3a9a2cbbc44c28889bacca49eb91cdd645eb8fe5.

Change-Id: I3897d8da5026ddc470989e3f239540286e89df4d
Reviewed-on: https://go-review.googlesource.com/33922
Reviewed-by: Alan Donovan <adonovan@google.com>
2 files changed