Our build attempts to turn on dwarf64 if the flag is supported, which it is with clang, but not with dwarf4 which is what clang defaults too. This results in an seg fault when debugging with GDB like this:

0xffffffffffffffff ???
---------------------
/data/mci/f4e13283150adfd2356a788ccb8aaf0a/toolchain-builder/tmp/build-gdb-v4.sh-mGA/src/gdb-12.1/gdb/dwarf2/read.c:6628: internal-error: cutu_reader: Assertion `this_cu->length == cu->header.get_length ()' failed.
A problem internal to GDB has been detected, 

We need to force clangs default to dwarg5 or force clang builds to dwarf32.

Workarounds:
Set DWARF_VERSION=5 on the scons command line

OR

Set DWARF_WIDTH=32 on the scons command line