[Issue 20510] Make backtrace code read the dSYM data

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=20510
Issue 20510 depends on issue 20460, which changed state.

Issue 20460 Summary: [OSX] DMD writes the same address everywhere in DWARF debug infos
https://issues.dlang.org/show_bug.cgi?id=20460

           What    |Removed                     |Added
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             Status|NEW                         |RESOLVED
         Resolution|---                         |FIXED

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