Definitions of variables inside functions should be located in a scope
different from function's arguments scope.

Change-Id: I89fe1f527681c68963f4a69c71b78975787a410c
Reviewed-on: https://swiftshader-review.googlesource.com/4180Reviewed-by: Nicolas Capens <capn@google.com>
Tested-by: Veranika Liaukevich <veranika@google.com>