We were pruning type-local subroutine DIEs if their context is unused
despite us later needing those DIEs as abstract origins for inlines.
The patch makes code already present for -fvar-tracking-assignments
unconditional.

2020-01-20  Richard Biener  <rguenther@suse.de>

	PR debug/92763
	* dwarf2out.c (prune_unused_types): Unconditionally mark
	called function DIEs.

	* g++.dg/debug/pr92763.C: New testcase.