Fix -Wodr in GCC LTO builds

I've tested GCC 10 and 11, which exhibit the problem, and 8, which
doesn't.

rtgui/controllines.cc

@@ -28,6 +28,9 @@
 
 using namespace rtengine;
 
+namespace
+{
+
 enum GeometryIndex {
     MO_CANVAS,
     MO_OBJECT_COUNT,
@@ -46,9 +49,6 @@ enum GeometryOffset {
     OFFSET_END = (MO_OBJECT_COUNT + ::ControlLine::END) % ::ControlLine::OBJECT_COUNT,
 };
 
-namespace
-{
-
 /**
  * Returns true if the object matches the offset.
  */

rtgui/gradient.cc

@@ -12,6 +12,9 @@
 using namespace rtengine;
 using namespace rtengine::procparams;
 
+namespace
+{
+
 enum GeometryIndex {
     H_LINE,
     V_LINE,
@@ -20,6 +23,8 @@ enum GeometryIndex {
     CENTER_CIRCLE,
 };
 
+}
+
 Gradient::Gradient () : FoldableToolPanel(this, "gradient", M("TP_GRADIENT_LABEL"), false, true), EditSubscriber(ET_OBJECTS), lastObject(-1), draggedPointOldAngle(-1000.)
 {
 

rtgui/spot.cc

@@ -29,6 +29,9 @@
 using namespace rtengine;
 using namespace rtengine::procparams;
 
+namespace
+{
+
 enum GeometryIndex {
     MO_TARGET_DISK,
     MO_SOURCE_DISC,
@@ -47,6 +50,8 @@ enum GeometryIndex {
     VISIBLE_OBJECT_COUNT
 };
 
+}
+
 Spot::Spot() :
     FoldableToolPanel(this, "spot", M ("TP_SPOT_LABEL"), true, true),
     EditSubscriber(ET_OBJECTS),