cmd/snap-seccomp/main_test.go: add one more syscall for arm64

[jdstrand]

I tested this locally on dragonboard in classic by running:

$ go build -v github.com/snapcore/snapd/... && go test -v github.com/snapcore/snapd/cmd/snap-seccomp
...
=== RUN   Test
OK: 11 passed
--- PASS: Test (355.58s)
PASS
ok  	github.com/snapcore/snapd/cmd/snap-seccomp	355.600s

[zyga]

+1

[codecov-io]

Codecov Report

Merging #3834 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #3834   +/-   ##
=======================================
  Coverage   75.74%   75.74%           
=======================================
  Files         409      409           
  Lines       35388    35388           
=======================================
  Hits        26804    26804           
  Misses       6688     6688           
  Partials     1896     1896

Impacted Files	Coverage Δ
interfaces/sorting.go	98.71% <0%> (-1.29%)	⬇️
overlord/ifacestate/helpers.go	62.33% <0%> (ø)	⬆️
cmd/snap/cmd_aliases.go	95% <0%> (+1.66%)	⬆️

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[jdstrand]

Two approvals, thanks! Merging.