Make FileSpec::Dump use FileSpec::GetPath(), not the other way around.

Summary:
Fix FileSpec::Dump() to output denormalized path.

See D9942 for previous discussions.

Reviewers: zturner

Reviewed By: zturner

Subscribers: lldb-commits

Differential Revision: http://reviews.llvm.org/D10077

llvm-svn: 238440