Fixed typos where end() was used instead of begin()

Bug b/137554711

Change-Id: I5faff14d400a644146501a941c35d503535355c4
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/34111Tested-by: Alexis Hétu <sugoi@google.com>
Presubmit-Ready: Alexis Hétu <sugoi@google.com>
Kokoro-Presubmit: kokoro <noreply+kokoro@google.com>
Reviewed-by: Nicolas Capens <nicolascapens@google.com>