Tests: Fix RunCMake.Framework ios arch for Xcode 9

Xcode 9 comes with the iPhoneOS 11.0 SDK that does not support the
`armv7` architecture.  For this SDK version and newer, use `arm64`.
17 jobs for test-macos-updates
Status Name Job ID Coverage
  External
passed cdash

passed cmake-moonshade-osx-debug-ninja

00:08:13

passed cmake-moonshade-osx-release-makefiles

00:09:07

passed ghostflow-branch-check-master

passed ghostflow-commit-check

passed ghostflow-stager

failed cmake-moonshade-osx-debug-ninja

00:00:12

passed ghostflow-stager

passed ghostflow-stager

passed ghostflow-stager

passed ghostflow-stager

passed ghostflow-stager

passed ghostflow-stager

passed ghostflow-stager

passed ghostflow-stager

passed ghostflow-stager

passed ghostflow-stager