This patch adds line numbers to perf jitdump records emitted by the
PerfSupportPlugin, by parsing and using a DWARFContext from preserved debug
sections.
To avoid making the OrcJIT library depend on DebugInfoDWARF this patch
introduces a new OrcDebugging library.
Reviewed By: lhames
Differential Revision: https://reviews.llvm.org/D146391
