Add the missing dependency from WSI -> System.

Bug: b/146051794
Change-Id: I15a48f37d764c339c8c032589625b6d173df76b9
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/40974Reviewed-by: Antonio Maiorano <amaiorano@google.com>
Reviewed-by: Alexis Hétu <sugoi@google.com>
Tested-by: Ben Clayton <bclayton@google.com>