SPIR-V: Fix const constructors with single scalar These constructors may be generated because of RemoveArrayLengthTraverser. Bug: chromium:332546345 Change-Id: I5b81ded59ba91b0083b14280f5a61b03b9d4ca43 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/5435713 Reviewed-by: Geoff Lang <geofflang@chromium.org> Commit-Queue: Geoff Lang <geofflang@chromium.org> Auto-Submit: Shahbaz Youssefi <syoussefi@chromium.org>