[cmake] Fix LLVM_LINK_LLVM_DYLIB build, again

The llvm_config hack for lldb-server is only necessary for !DYLIB builds, as
otherwise we would get unresolved symbols from lldb libraries which do not track
their dependencies correctly (all of them). In a DYLIB build, the so will
already be added to the link dependencies and we can use that to resolve all
missing symbols.

The proper fix for this would be to have each lldb library track its
dependencies correctly.

llvm-svn: 291555