array_pod_sort: Since we're checking the length anyways also ignore one-element ranges

Sorting them is obviously a noop and we can skip the libc call. This is
surprisingly common in clang. NFC.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@232265 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed