Xcode: De-duplicate -dynamiclib/-bundle flags for SHARED/MODULE libraries

Xcode automatically adds a flag matching the generated `LIBRARY_STYLE`:

* For SHARED libraries we've been duplicating `-dynamiclib` with a copy
  in `CMAKE_SHARED_LIBRARY_CREATE_<LANG>_FLAGS`.  Remove it for Xcode.

* For MODULE libraries we've been not duplicating `-bundle` only by accident.
  Since commit 586a9427d3 (ENH: Created target property INSTALL_NAME_DIR...,
  2006-02-24, v2.4.0~418) we've looked up `CMAKE_<LANG>_LINK_FLAGS`, meant
  for EXECUTABLEs, instead of `CMAKE_SHARED_MODULE_CREATE_<LANG>_FLAGS`.
  Switch to the latter, but remove `-bundle` for Xcode.