Fix various cmake dependency warnings

indra/media_plugins/example/CMakeLists.txt

@@ -57,14 +57,6 @@ target_link_libraries(media_plugin_example
   ${PLUGIN_API_WINDOWS_LIBRARIES}
 )
 
-add_dependencies(media_plugin_example
-  ${LLPLUGIN_LIBRARIES}
-  ${MEDIA_PLUGIN_BASE_LIBRARIES}
-  # Using ${LLCOMMON_LIBRARIES} here drags in a whole bunch of Boost stuff
-  # that only produces CMake warnings about nonexistent dependencies.
-  llcommon
-)
-
 if (WINDOWS)
   set_target_properties(
     media_plugin_example

indra/media_plugins/gstreamer010/CMakeLists.txt

@@ -65,11 +65,3 @@ target_link_libraries(media_plugin_gstreamer010
   ${PLUGIN_API_WINDOWS_LIBRARIES}
   ${GSTREAMER010_LIBRARIES}
 )
-
-add_dependencies(media_plugin_gstreamer010
-  ${LLPLUGIN_LIBRARIES}
-  ${MEDIA_PLUGIN_BASE_LIBRARIES}
-  ${LLCOMMON_LIBRARIES}
-)
-
-

indra/media_plugins/libvlc/CMakeLists.txt

@@ -58,22 +58,6 @@ target_link_libraries(media_plugin_libvlc
   ${PLUGIN_API_WINDOWS_LIBRARIES}
 )
 
-add_dependencies(media_plugin_libvlc
-  ${LLPLUGIN_LIBRARIES}
-  ${MEDIA_PLUGIN_BASE_LIBRARIES}
-##${LLCOMMON_LIBRARIES}
-  # Just say 'llcommon' here. LLCOMMON_LIBRARIES is specified for use in
-  # target_link_libraries: it includes several Boost libraries, which are
-  # absolutely NOT dependencies in the sense intended here. Those Boost
-  # library macros, in turn, specify 'debug' and 'optimized' and a different
-  # library name for each, producing several wordy errors:
-  # Policy CMP0046 is not set: Error on non-existent dependency in
-  # add_dependencies.
-  # Really, the only dependency we should mention from LLCOMMON_LIBRARIES is
-  # llcommon itself.
-  llcommon
-)
-
 if (WINDOWS)
   set_target_properties(
     media_plugin_libvlc