Reland "[llvm][dsymutil] Add DW_TAG_imported_declaration to accelerator table"

This relands the commit previously reverted in
`8570bee5` due to failures on linux.

The problem was that the test executable was built with absolute
OSO prefix paths. This re-commit adds a modified version of the
executable that strips the absolute OSO prefix paths and makes
sure the test appends the OSO prefix appropriately (via the appropriate
dsymutil flags).

Differential Revision: https://reviews.llvm.org/D143458