[CMake] Add install targets for utilities to LLVM exports if LLVM_INSTALL_UTILS=ON
[CMake] Add install targets for utilities to LLVM exports if LLVM_INSTALL_UTILS=ON

Summary: D56606 was only appending target names to the `LLVM_EXPORTS`/`LLVM_EXPORTS_BUILDTREE_ONLY` properties. Targets showed up correctly in the build-tree `LLVMExports.cmake`, but they were missing in the installed one (as we found in https://bugs.llvm.org/show_bug.cgi?id=40443), because install did not register them explicitly.

Reviewers: mgorny, smeenai, beanz, gottesmm, dschuff, tstellar, serge-sans-paille

Reviewed By: smeenai

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D57383

git-svn-id: 0ff597fd157e6f4fc38580e8d64ab130330d2411@352869 91177308-0d34-0410-b5e6-96231b3b80d8

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