When an unsupported structure type was encountered this would lead to an
infinite loop.

Bug b/117974925

Change-Id: I0ba68e80a162ee631ae122b765cf8ea1149b3a3b
Reviewed-on: https://swiftshader-review.googlesource.com/c/22510Tested-by: Nicolas Capens <nicolascapens@google.com>
Reviewed-by: Corentin Wallez <cwallez@google.com>
Reviewed-by: Alexis Hétu <sugoi@google.com>