Also add implementations of multiplication and right shift for Long type.

Bug b/126873455

Change-Id: I9952c2b9a3feca6a7741cd02e2295340935e4447
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/25988Tested-by: Nicolas Capens <nicolascapens@google.com>
Reviewed-by: Chris Forbes <chrisforbes@google.com>