fix infinite loop build bug on ppc64le for R v4.0.0

[branfosj]

(created using eb --new-pr)

R 4.0.0 build gets stuck in an infinite loop on ppc64le (https://stat.ethz.ch/pipermail/r-devel/2020-April/079382.html). This adds the upstream fix.

[branfosj]

Test report by @branfosj
SUCCESS
Build succeeded for 1 out of 1 (1 easyconfigs in this PR)
bear-pg0211u03a.bear.cluster - Linux centos linux 7.8.2003, x86_64, Intel(R) Xeon(R) Gold 6248 CPU @ 2.50GHz (cascadelake), Python 3.6.8
See https://gist.github.com/ce1c267bf97a13c5d8214be2dbba3112 for a full test report.

[branfosj]

Test report by @branfosj
SUCCESS
Build succeeded for 1 out of 1 (1 easyconfigs in this PR)
bear-pg0305u03a.bear.cluster - Linux RHEL 7.6, POWER, 8335-GTX (power9le), Python 3.6.8
See https://gist.github.com/30d6b49c579efd68d74d4029fc024c9c for a full test report.

[boegel]

@boegelbot please test @ generoso

[boegelbot]

@boegel: Request for testing this PR well received on generoso

PR test command 'EB_PR=11428 EB_ARGS= /apps/slurm/default/bin/sbatch --job-name test_PR_11428 ~/boegelbot/eb_from_pr_upload_generoso.sh' executed!

• exit code: 0
• output:

Submitted batch job 8009

Test results coming soon (I hope)...

- notification for comment with ID 703511404 processed

Message to humans: this is just bookkeeping information for me,
it is of no use to you (unless you think I have a bug, which I don't).

[boegelbot]

Test report by @boegelbot
SUCCESS
Build succeeded for 1 out of 1 (1 easyconfigs in this PR)
generoso-x-2 - Linux centos linux 8.2.2004, x86_64, Intel(R) Xeon(R) CPU E5-2667 v3 @ 3.20GHz (haswell), Python 3.6.8
See https://gist.github.com/a45d8a48c43f2eec7045f0fffbce3340 for a full test report.

[boegel]

Test report by @boegel
SUCCESS
Build succeeded for 1 out of 1 (1 easyconfigs in this PR)
node3404.kirlia.os - Linux centos linux 7.8.2003, x86_64, Intel(R) Xeon(R) Gold 6240 CPU @ 2.60GHz (cascadelake), Python 2.7.5
See https://gist.github.com/6c80d71554f8bd7fe440ae4dbaf404c3 for a full test report.

[boegel]

lgtm

[boegel]

Going in, thanks @branfosj!