set filename on file read for more types

the new loaders were missing the line to set the output filename, so
`vipsheader fred.pdf` was not displaying the filename correctly

TODO

@@ -1,23 +1,9 @@
-- try:
-
-	$ vipsheader blankpage.pdf 
-	temp-0: 595x842 uchar, 4 bands, srgb, pdfload
-
-  filename is not set?
-
-  try other files in test/images
-
 - try adding a coz progress point to vipsthumbnail's main loop
 
   see
 
 	https://github.com/plasma-umass/coz
 
-
-
-
-
-
 - tiff write does not support [strip]
 
 - add more webp tests to py suite

libvips/foreign/gifload.c

@@ -605,6 +605,8 @@ vips_foreign_load_gif_file_header( VipsForeignLoad *load )
 	if( vips_foreign_load_gif_open( gif, file->filename ) ) 
 		return( -1 ); 
 
+	VIPS_SETSTR( load->out->filename, file->filename );
+
 	return( vips_foreign_load_gif_header( load ) );
 }
 

libvips/foreign/jpeg2vips.c

@@ -1174,6 +1174,8 @@ vips__jpeg_read_file( const char *filename, VipsImage *out,
 	if( vips__jpeg_read( jpeg, out, header_only ) ) 
 		return( -1 );
 
+	VIPS_SETSTR( out->filename, filename );
+
 	/* We can kill off the decompress early if this is just a header read.
 	 * This saves an fd during read.
 	 */

libvips/foreign/jpegload.c

@@ -204,8 +204,6 @@ vips_foreign_load_jpeg_file_header( VipsForeignLoad *load )
 		TRUE, jpeg->shrink, jpeg->fail, FALSE, jpeg->autorotate ) ) 
 		return( -1 );
 
-	VIPS_SETSTR( load->out->filename, file->filename );
-
 	return( 0 );
 }
 

libvips/foreign/pdfload.c

@@ -543,6 +543,8 @@ vips_foreign_load_pdf_file_header( VipsForeignLoad *load )
 		return( -1 ); 
 	}
 
+	VIPS_SETSTR( load->out->filename, file->filename );
+
 	return( vips_foreign_load_pdf_header( load ) );
 }
 

libvips/foreign/svgload.c

@@ -308,6 +308,8 @@ vips_foreign_load_svg_file_header( VipsForeignLoad *load )
 		return( -1 ); 
 	}
 
+	VIPS_SETSTR( load->out->filename, file->filename );
+
 	return( vips_foreign_load_svg_header( load ) );
 }