Separate install directory for each worktree

The install directory will be <Worktree>/install, right next to the build and
source dirs, and it will be exported in LLVM_INSTALL.

Note that this won't affect existing worktree directories, you should either
nuke the build directories or manually update CMakeCache.txt for them.

Change-Id: I8bb80f8d86d9d2f8d02940fbbd8a2c8b5b1a05e3
2 files changed