This bumps OSL to 1.11.10.0. OSL Has a new build time dependency: Clang, and more importantly it expects clang and llvm to share a library folder, which it previously for us did not. This patch changes: -OSL Update to 1.11.10.0 -refactor the llvm/clang/clang-tools-extra builds into the llvm build using the llvm-project tarball for building that has all of the subprojects in it. -update ispc/openmp builds since clang no longer its own dependency and they have to depend on the llvm build now. -Update the windows builder to use the 64 bit host tools since it ran out of ram linking clang -Since OSL now needs clang to link successfully a findclang.cmake has been provided for linux/OSX Differential Revision: https://developer.blender.org/D10212 Reviewed By: brecht, sebbas, sybren