Test issue: legion - Illegal instruction (core dumped) when running run.sh validation test

Summary:
After building spec according to spack.yaml, legion's validation test fails at run time when executing run.sh due to an "Illegal instruction"

Steps to reproduce:

$ ./setup.sh
$ ./clean.sh
$ ./compile.sh
$ ./run.sh

Error output:

sbosch@instinct:~/instinctE4S-22.05/testsuite/validation_tests/legion$ ./run.sh
4sjbscc
g3tu5cd
++ mktemp ./tmp.XXXXXXX
+ TMPFILE=./tmp.3Paqy6j
+ cd build
+ ./legion
./run.sh: line 10: 3983381 Illegal instruction     (core dumped) ./legion > ${TMPFILE}

spack debug report:

• Spack: 0.18.0 (c09bf37ff690c29779a342670cf8a171ad1b9233)
• Python: 3.8.10
• Platform: linux-ubuntu20.04-broadwell
• Concretizer: clingo

Helpful files:
(Changed to .txt extension for upload)
run.sh.txt
spack.yaml.txt

Additional Info:

• Test matches the test from the legion source in legion/tutorial/08_multiple_partitions/multiple_partitions.cc

Package Maintainers and Interested Parties:

• @pmccormick
• @streichler
• @wspear

Start with validation_tests/legion/run.sh and the attached spack.yaml, then reproduce with setup.sh, clean.sh, compile.sh, and run.sh. Compare the test with legion/tutorial/08_multiple_partitions/multiple_partitions.cc and inspect the reported build and platform details. Done means the Legion validation test runs without the illegal-instruction failure and completes its expected validation.