Allow DWARFDebugInfoEntryMinimal::getSubroutineName to resolve cross-unit references.

Summary: getSubroutineName is currently only used by llvm-symbolizer, thus add a binary test containing a cross-cu inlining example.

Reviewers: samsonov, dblaikie

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D5394
[dwarfdump] Dump full filenames as DW_AT_(decl|call)_file attribute values

Reviewers: dblaikie samsonov

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D5192