Fix comment describing alternative GPU backends and remove redundant for renderscript selection code.
Fix comment describing alternative GPU backends and remove redundant
for renderscript selection code.


Former-commit-id: 6d5284e6f9ccfc2dfa4133cd8cd2f3c1471722bb
Trass3r/Halide,Trass3r/Halide,Trass3r/Halide,darkbuck/Halide,darkbuck/Halide,darkbuck/Halide,darkbuck/Halide,darkbuck/Halide,darkbuck/Halide,Trass3r/Halide,Trass3r/Halide,Trass3r/Halide,darkbuck/Halide,Trass3r/Halide