[sourcekit] Fix swift library dependencies

Now that we're in the same repo, use cmake targets instead of paths so
we get correct dependencies.

Author: benlangmuir

Diff for: tools/SourceKit/CMakeLists.txt

@@ -111,9 +111,6 @@ macro(add_sourcekit_library name)
     if("${dep}" MATCHES "^clang")
       set(dep "${LLVM_LIBRARY_OUTPUT_INTDIR}/lib${dep}.a")
     endif()
-    if("${dep}" MATCHES "^swift")
-      set(dep "${SWIFT_LIBRARY_OUTPUT_INTDIR}/lib${dep}.a")
-    endif()
     if("${dep}" STREQUAL "cmark")
       set(dep "${CMARK_LIBRARY_DIR}/lib${dep}.a")
     endif()