Revert "[Support][ThinLTO] Move ThinLTO caching to LLVM Support library"

clang/lib/CodeGen/BackendUtil.cpp

lld/COFF/LTO.cpp

lld/ELF/LTO.cpp

lld/MachO/LTO.cpp

lld/wasm/LTO.cpp

llvm/include/llvm/LTO/Caching.h

llvm/include/llvm/LTO/LTO.h

llvm/include/llvm/LTO/legacy/LTOCodeGenerator.h

llvm/include/llvm/Support/Caching.h

llvm/lib/LTO/CMakeLists.txt

llvm/lib/LTO/Caching.cpp

llvm/lib/LTO/LTOCodeGenerator.cpp

llvm/lib/Support/CMakeLists.txt

llvm/tools/gold/gold-plugin.cpp

llvm/tools/llvm-lto/llvm-lto.cpp

llvm/tools/llvm-lto2/llvm-lto2.cpp