CMake: Only export Tools target if BUILD_TOOLS is on

[skip ci]

pandatool/CMakeLists.txt

@@ -47,5 +47,7 @@ add_subdirectory(src/xfile)
 add_subdirectory(src/xfileegg)
 add_subdirectory(src/xfileprogs)
 
-export_targets(Tools)
+if(BUILD_TOOLS)
+  export_targets(Tools)
+endif()
 export_targets(ToolsDevel NAMESPACE "Panda3D::Tools::" COMPONENT ToolsDevel)