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
