Fix windows build.
Fix windows build.

Remove duplicate definitions of Extract and Insert for UInt4

Change-Id: Ib2d54606ead6b953b93f28e9f0dfd7987b1da774
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/28848
Presubmit-Ready: Ben Clayton <1f693eb7158dc33015048c09d6712f74dabddf79@google.com>
Reviewed-by: Nicolas Capens <51edc787c30f24c4904e8ffbb5523c3a9f7a451d@google.com>
Tested-by: Ben Clayton <1f693eb7158dc33015048c09d6712f74dabddf79@google.com>

google/swiftshader,bkaradzic/SwiftShader,google/swiftshader,bkaradzic/SwiftShader,bkaradzic/SwiftShader,google/swiftshader,bkaradzic/SwiftShader,bkaradzic/SwiftShader