Fix building of tutorials in the CMake build. We now make declaration of tutorials explicit because they don't all have the same requirements (e.g. some need libpng).
Fix building of tutorials in the CMake build. We now make declaration
of tutorials explicit because they don't all have the same requirements
(e.g. some need libpng).

Lesson 10 is more complicated to build because it builds and runs a
generator whose output we links against. I'm not sure if this will work
on all platforms so I've added option (BUILD_AOT_TUTORIAL) that allows
building of this tutorial to be disabled.


Former-commit-id: f1364f381c52db975020a5551bf64e70804ee860
darkbuck/Halide,darkbuck/Halide,Trass3r/Halide,Trass3r/Halide,darkbuck/Halide,Trass3r/Halide,darkbuck/Halide,darkbuck/Halide,Trass3r/Halide,Trass3r/Halide,Trass3r/Halide,Trass3r/Halide,darkbuck/Halide,darkbuck/Halide