fix gazebo_plugins runtime error: undefined symbol (ethz-asl#667)

rotors_gazebo_plugins/CMakeLists.txt

@@ -211,13 +211,18 @@ file(GLOB msgs msgs/*.proto)
 PROTOBUF_GENERATE_CPP(PROTO_SRCS PROTO_HDRS ${msgs})
 
 # Create a shared library of protobuf messages (.so extension on Linux platforms)
-add_library(mav_msgs SHARED ${PROTO_SRCS})
-target_link_libraries(mav_msgs ${PROTOBUF_LIBRARY} gazebo_msgs)
+# add_library(mav_msgs SHARED ${PROTO_SRCS})
+# target_link_libraries(mav_msgs ${PROTOBUF_LIBRARY} gazebo_msgs)
 
 # This causes mav_msgs to be linked with every created library in this file from this
 # point forward.
 # NOTE: This is deprecated, should be using target_link_libraries instead
-link_libraries(mav_msgs)
+# link_libraries(mav_msgs)
+
+add_library(mav_proto_msgs SHARED ${PROTO_SRCS})
+target_link_libraries(mav_proto_msgs ${PROTOBUF_LIBRARY} gazebo_msgs)
+list (APPEND targets_to_install mav_proto_msgs)
+
 
 # ============================================== #
 # ==================== CATKIN ================== #
@@ -246,6 +251,7 @@ if (NOT NO_ROS)
   endif()
 endif()
 
+list(APPEND target_linking_LIBRARIES mav_proto_msgs)
 
 # Including GAZEBO_MSG_INCLUDE_DIRS here allows the .cpp files generated by custom .proto files to find
 # the .cpp/hpp files generated by the built-in Gazebo .proto files