PROJ6: more context sharing

Author: rouault

mapkmlrenderer.cpp

@@ -549,11 +549,12 @@ int KmlRenderer::checkProjection(mapObj *map)
     }
     strcpy(epsg_string, "epsg:4326" );
     msInitProjection(&out);
+    msProjectionInheritContextFrom(&out, projection);
     msLoadProjectionString(&out, epsg_string);
 
     sRect = map->extent;
     msProjectRect(projection, &out, &sRect);
-    msFreeProjection(projection);
+    msFreeProjectionExceptContext(projection);
     msLoadProjectionString(projection, epsg_string);
 
     /*change also units and extents*/

mapogr.cpp

@@ -966,7 +966,7 @@ static int msOGRSpatialRef2ProjectionObj(OGRSpatialReferenceH hSRS,
 {
 #ifdef USE_PROJ
   // First flush the "auto" name from the projargs[]...
-  msFreeProjection( proj );
+  msFreeProjectionExceptContext( proj );
 
   if (hSRS == NULL || OSRIsLocal( hSRS ) ) {
     // Dataset had no set projection or is NonEarth (LOCAL_CS)...
@@ -1288,6 +1288,7 @@ msOGRFileOpen(layerObj *layer, const char *connection )
 
   psInfo->nTileId = 0;
   msInitProjection(&(psInfo->sTileProj));
+  msProjectionInheritContextFrom(&(psInfo->sTileProj),&(layer->projection));
   psInfo->poCurTile = NULL;
   psInfo->rect_is_defined = false;
   psInfo->rect.minx = psInfo->rect.maxx = 0;