Use a parameterized dict and simplify an iteration in xcode-locator.
Use a parameterized dict and simplify an iteration in xcode-locator.

This raises the minimum version with which xcode-locator must be built
to Xcode 7.

Changes suggested by davg@ during the review of another change to the
xcode-locator.

RELNOTES: None.
PiperOrigin-RevId: 206949696

dslomov/bazel,dropbox/bazel,twitter-forks/bazel,dslomov/bazel-windows,dslomov/bazel-windows,cushon/bazel,meteorcloudy/bazel,akira-baruah/bazel,dslomov/bazel-windows,akira-baruah/bazel,twitter-forks/bazel,dslomov/bazel-windows,aehlig/bazel,dslomov/bazel-windows,davidzchen/bazel,bazelbuild/bazel,dslomov/bazel,dropbox/bazel,perezd/bazel,akira-baruah/bazel,aehlig/bazel,katre/bazel,cushon/bazel,cushon/bazel,dslomov/bazel-windows,perezd/bazel,cushon/bazel,davidzchen/bazel,meteorcloudy/bazel,davidzchen/bazel,meteorcloudy/bazel,meteorcloudy/bazel,twitter-forks/bazel,davidzchen/bazel,davidzchen/bazel,perezd/bazel,cushon/bazel,davidzchen/bazel,werkt/bazel,ButterflyNetwork/bazel,safarmer/bazel,ulfjack/bazel,katre/bazel,aehlig/bazel,dslomov/bazel,bazelbuild/bazel,twitter-forks/bazel,ButterflyNetwork/bazel,twitter-forks/bazel,katre/bazel,werkt/bazel,ulfjack/bazel,werkt/bazel,ButterflyNetwork/bazel,ulfjack/bazel,katre/bazel,bazelbuild/bazel,dropbox/bazel,safarmer/bazel,aehlig/bazel,dslomov/bazel,dslomov/bazel,dslomov/bazel,werkt/bazel,katre/bazel,meteorcloudy/bazel,ulfjack/bazel,akira-baruah/bazel,dropbox/bazel,perezd/bazel,perezd/bazel,safarmer/bazel,werkt/bazel,aehlig/bazel,bazelbuild/bazel,dslomov/bazel,dropbox/bazel,ButterflyNetwork/bazel,ButterflyNetwork/bazel,ulfjack/bazel,werkt/bazel,katre/bazel,perezd/bazel,davidzchen/bazel,cushon/bazel,bazelbuild/bazel,aehlig/bazel,akira-baruah/bazel,safarmer/bazel,meteorcloudy/bazel,bazelbuild/bazel,safarmer/bazel,safarmer/bazel,ButterflyNetwork/bazel,twitter-forks/bazel,aehlig/bazel,meteorcloudy/bazel,ulfjack/bazel,perezd/bazel,dropbox/bazel,akira-baruah/bazel,ulfjack/bazel,twitter-forks/bazel