[COFF] Don't treat DWARF sections as GC roots

DWARF sections are typically live and not COMDAT, so they would be
treated as GC roots. Enabling DWARF would essentially keep all code with
debug info alive, preventing any section GC.

Fixes PR45273

Reviewed By: mstorsjo, MaskRay

Differential Revision: https://reviews.llvm.org/D76935