DRTVWR-418: Try to clean up numerous CMake CMP0046 warnings.

indra/media_plugins/libvlc/CMakeLists.txt

@@ -61,7 +61,17 @@ target_link_libraries(media_plugin_libvlc
 add_dependencies(media_plugin_libvlc
   ${LLPLUGIN_LIBRARIES}
   ${MEDIA_PLUGIN_BASE_LIBRARIES}
-  ${LLCOMMON_LIBRARIES}
+##${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)