fix build with libheif save buit not load

We had some definitions inside the #ifdef HEIFLOAD.

Thanks estepnv

https://github.com/libvips/libvips/issues/1844

ChangeLog

@@ -14,6 +14,7 @@
 - improve seek behaviour on pipes
 - add "speed" param to heifsave [lovell]
 - fix regression in C path for dilate / erode [kleisauke]
+- fix build with libheif save but no load [estepnv]
 
 9/8/20 started 8.10.1
 - fix markdown -> xml conversion in doc generation

libvips/foreign/heifload.c

@@ -68,12 +68,33 @@
 #include <vips/debug.h>
 #include <vips/internal.h>
 
-#ifdef HAVE_HEIF_DECODER
+/* These are shared with the encoder.
+ */
+#if defined(HAVE_HEIF_DECODER) || defined(HAVE_HEIF_ENCODER)
 
 #include <libheif/heif.h>
 
 #include "pforeign.h"
 
+void
+vips__heif_error( struct heif_error *error )
+{
+	if( error->code ) 
+		vips_error( "heif", "%s (%d.%d)", error->message, error->code,
+			error->subcode );
+}
+
+const char *vips__heif_suffs[] = { 
+	".heic",
+	".heif",
+	".avif",
+	NULL 
+};
+
+#endif /*defined(DECODE) || defined(ENCODE)*/
+
+#ifdef HAVE_HEIF_DECODER
+
 #define VIPS_TYPE_FOREIGN_LOAD_HEIF (vips_foreign_load_heif_get_type())
 #define VIPS_FOREIGN_LOAD_HEIF( obj ) \
 	(G_TYPE_CHECK_INSTANCE_CAST( (obj), \
@@ -200,14 +221,6 @@ vips_foreign_load_heif_dispose( GObject *gobject )
 		dispose( gobject );
 }
 
-void
-vips__heif_error( struct heif_error *error )
-{
-	if( error->code ) 
-		vips_error( "heif", "%s (%d.%d)", error->message, error->code,
-			error->subcode );
-}
-
 static int
 vips_foreign_load_heif_build( VipsObject *object )
 {
@@ -1055,13 +1068,6 @@ vips_foreign_load_heif_file_is_a( const char *filename )
 	return( vips_foreign_load_heif_is_a( buf, 12 ) );
 }
 
-const char *vips__heif_suffs[] = { 
-	".heic",
-	".heif",
-	".avif",
-	NULL 
-};
-
 static void
 vips_foreign_load_heif_file_class_init( VipsForeignLoadHeifFileClass *class )
 {