The add_dependencies call on compiler-rt-configure adds llvm-config and clang to the phony target, but not to the actual configure custom command. We need the dependency bound to the custom command so that it can't be re-ordered by Ninja.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@255798 91177308-0d34-0410-b5e6-96231b3b80d8