[BOLT] Rework debug info processing.

Summary:
Multiple improvements to debug info handling:
  * Add support for relocation mode.
  * Speed-up processing.
  * Reduce memory consumption.
  * Bug fixes.

The high-level idea behind the new debug handling is that we don't save
intermediate state for ranges and location lists. Instead we depend
on function and basic block address transformations to update the info
as a final post-processing step.

For HHVM in non-relocation mode the peak memory went down from 55GB to 35GB. Processing time went from over 6 minutes to under 5 minutes.

(cherry picked from FBD5113431)