Subzero, MIPS32: Remove duplicate functionalities
Subzero, MIPS32: Remove duplicate functionalities

Removes lowering functions functionalities already covered by
genTargetHelperCallFor. Adds error messages for appropriate cases.

R=stichnot@chromium.org

Review URL: https://codereview.chromium.org/2358123002 .

Patch from Srdjan Obucina <Srdjan.Obucina@imgtec.com>.

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