dwarf: add support for .eh_frame_hdr when unwinding

- .eh_frame_hdr contains a binary-searchable data structure for finding an FDE. If present, we can use this
section to avoid having to parse the entire FDE/CIE list in the binary, instead only entries that are actually
required for unwinding are read.
- rework the inputs pc-relative pointer decoding to support both already-mapped sections as well as sections
mapped from a file
- store the VirtualMachine on UnwindContext so the allocations can be reused
5781016c35kcbanner committed on 7/21/2023, 2:58:13 AMparentdd20357
3 files changedLine totals unavailable