Remove build RUNPATH from installed libGrid3D.so

backport #676

Signed-off-by: Guilhem Saurel <guilhem.saurel@laas.fr>

Author: nim65s

src/plugins/grid_config/CMakeLists.txt

@@ -7,8 +7,14 @@ ign_gui_add_plugin(GridConfig
     ${IGNITION-RENDERING_LIBRARIES}
 )
 
-# Also install as Grid3D, which was a legacy plugin with a subset of features
-install (
-  FILES $<TARGET_FILE:GridConfig>
-  RENAME ${CMAKE_SHARED_LIBRARY_PREFIX}Grid3D${CMAKE_SHARED_LIBRARY_SUFFIX}
-  DESTINATION ${IGNITION_GUI_PLUGIN_INSTALL_DIR})
+# Also install Grid3D (a legacy plugin with a subset of features) by copying the installed GridConfig library. This ensures the correct RUNPATH is used.
+
+install(CODE "
+  if(EXISTS \"\${CMAKE_INSTALL_PREFIX}/${IGNITION_GUI_PLUGIN_RELATIVE_INSTALL_DIR}/libGridConfig.so\")
+    execute_process(COMMAND ${CMAKE_COMMAND} -E copy_if_different
+    \"\${CMAKE_INSTALL_PREFIX}/${IGNITION_GUI_PLUGIN_RELATIVE_INSTALL_DIR}/libGridConfig.so\"
+    \"\${CMAKE_INSTALL_PREFIX}/${IGNITION_GUI_PLUGIN_RELATIVE_INSTALL_DIR}/libGrid3D.so\")
+  else()
+    message(WARNING \"Source file for Grid3D (legacy plugin) copy not found, skipping copy: \${CMAKE_INSTALL_PREFIX}/${IGNITION_GUI_PLUGIN_RELATIVE_INSTALL_DIR}/libGridConfig.so\")
+  endif()
+")