This block declares variables, so should be scoped.

Bug: b/145351270
Change-Id: I90b750a81f4ff93f1c618a2ae969fa321961673c
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/39311Tested-by: Ben Clayton <bclayton@google.com>
Reviewed-by: Nicolas Capens <nicolascapens@google.com>