add scripts to doxygen for subzero
add scripts to doxygen for subzero

BUG=
R=stichnot@chromium.org

Review URL: https://codereview.chromium.org/1572143002 .

Patch from Reed Kotler <rkotlerimgtec@gmail.com>.

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