Install libLLVM if needed with LLVM_INSTALL_TOOLCHAIN_ONLY
Install libLLVM if needed with LLVM_INSTALL_TOOLCHAIN_ONLY

Summary:
When LLVM_LINK_LLVM_DYLIB is set, the libLLVM shared
library needs to be installed in the toolchain.  Without
this chanage LLVM_INSTALL_TOOLCHAIN_ONLY combined with
LLVM_LINK_LLVM_DYLIB results in a broken install.

Patch by Sam Clegg

Differential Revision: https://reviews.llvm.org/D24676

git-svn-id: 0ff597fd157e6f4fc38580e8d64ab130330d2411@281763 91177308-0d34-0410-b5e6-96231b3b80d8

llvm-mirror/llvm,apple/swift-llvm,apple/swift-llvm,GPUOpen-Drivers/llvm,apple/swift-llvm,llvm-mirror/llvm,apple/swift-llvm,llvm-mirror/llvm,apple/swift-llvm,GPUOpen-Drivers/llvm,llvm-mirror/llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,GPUOpen-Drivers/llvm,GPUOpen-Drivers/llvm,GPUOpen-Drivers/llvm,apple/swift-llvm,apple/swift-llvm,GPUOpen-Drivers/llvm,llvm-mirror/llvm,llvm-mirror/llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,apple/swift-llvm,llvm-mirror/llvm