Fix build with exiv2 >=0.28.0.

Index: src/gimplensfun.cpp
--- src/gimplensfun.cpp.orig
+++ src/gimplensfun.cpp
@@ -1032,7 +1032,7 @@ static void process_image (GimpDrawable *drawable) {
 //
 static int read_opts_from_exif(const char *filename) {
 
-    Exiv2::Image::AutoPtr Exiv2image;
+    Exiv2::Image::UniquePtr Exiv2image;
     Exiv2::ExifData exifData;
 
     const lfCamera  **cameras    = 0;
@@ -1060,7 +1060,7 @@ static int read_opts_from_exif(const char *filename) {
             return -1;
         }
     }
-    catch (Exiv2::AnyError& e) {
+    catch (Exiv2::Error& e) {
         if (DEBUG) {
             g_print ("exception on reading data. \n");
         }