Enable build with exiv2 <0.28

--- saga-gis/src/tools/io/io_grid_image/CMakeLists.txt.orig	2025-07-14 09:54:43
+++ saga-gis/src/tools/io/io_grid_image/CMakeLists.txt	2025-07-16 16:27:17
@@ -31,7 +31,7 @@
 		else() # non-msw
 			find_package(exiv2 QUIET)
  			if(exiv2_FOUND)
-				target_link_libraries(${PROJECT_NAME} Exiv2::exiv2lib)
+				target_link_libraries(${PROJECT_NAME} exiv2lib)
 				target_compile_definitions(${PROJECT_NAME} PRIVATE HAVE_EXIV2)
 			endif()
 		endif()
--- saga-gis/src/tools/io/io_grid_image/extract_exif_gps.cpp.orig	2025-07-14 09:54:43
+++ saga-gis/src/tools/io/io_grid_image/extract_exif_gps.cpp	2025-07-16 16:25:04
@@ -311,7 +311,7 @@
 				if( altIt != exifData.end() && altRefIt != exifData.end() && altIt->value().count() == 1 )
 				{
     				double 	Altitide = Convert_Rational( altIt->value(), 0 );
-					if( altRefIt->value().toUint32() == 1 ) Altitide *= -1;
+					if( altRefIt->value().toLong() == 1 ) Altitide *= -1;
 					pShape->Set_Value( 6, Altitide );
 					pShape->Set_Z( Altitide );
 					Alt_Message = "Found altitude";