deactivate postgis getextent function (#4039)

return an error instead of invalid extents to avoid peculiar behavior in
proj when reprojecting invalid values. this will also trigger a warning
in capabilities documents.

closes #4039

mappostgis.c

@@ -65,10 +65,6 @@
 #include "maptime.h"
 #include "mappostgis.h"
 
-#ifndef FLT_MAX
-#define FLT_MAX 25000000.0
-#endif
-
 #define FP_EPSILON 1e-12
 #define FP_EQ(a, b) (fabs((a)-(b)) < FP_EPSILON)
 #define FP_LEFT -1
@@ -2998,27 +2994,6 @@ int msPostGISLayerGetItems(layerObj *layer)
 #endif
 }
 
-/*
-** msPostGISLayerGetExtent()
-**
-** Registered vtable->LayerGetExtent function.
-**
-** TODO: Update to use proper PostGIS functions to pull
-** extent quickly and accurately when available.
-*/
-int msPostGISLayerGetExtent(layerObj *layer, rectObj *extent)
-{
-  if (layer->debug) {
-    msDebug("msPOSTGISLayerGetExtent called.\n");
-  }
-
-  extent->minx = extent->miny = -1.0 * FLT_MAX ;
-  extent->maxx = extent->maxy = FLT_MAX;
-
-  return MS_SUCCESS;
-
-}
-
 /*
  * make sure that the timestring is complete and acceptable
  * to the date_trunc function :
@@ -3373,7 +3348,7 @@ int msPostGISLayerInitializeVirtualTable(layerObj *layer)
   layer->vtable->LayerGetShape = msPostGISLayerGetShape;
   layer->vtable->LayerClose = msPostGISLayerClose;
   layer->vtable->LayerGetItems = msPostGISLayerGetItems;
-  layer->vtable->LayerGetExtent = msPostGISLayerGetExtent;
+  /* layer->vtable->LayerGetExtent = msPostGISLayerGetExtent; */
   layer->vtable->LayerApplyFilterToLayer = msLayerApplyCondSQLFilterToLayer;
   /* layer->vtable->LayerGetAutoStyle, not supported for this layer */
   layer->vtable->LayerCloseConnection = msPostGISLayerClose;