Check properly whether the XPM module has already been loaded

Check properly whether the XPM module has already been loaded

1999-10-27  Havoc Pennington  <hp@pobox.com>

* src/gdk-pixbuf-io.c (gdk_pixbuf_new_from_xpm_data): Check
properly whether the XPM module has already been loaded
(gdk_pixbuf_new_from_file): Check properly if loader module
was already loaded (was checking if load symbol was present
in order to decide whether to re-load; should check module !=
NULL, then load != NULL)
(image_handler_load): Check in present working directory,
makes it easier to debug for now
(file_formats): This array initializer was seriously on crack,
was assigning a function pointer to a GModule*

* src/testpixbuf.c (main): Change type of pixbuf_loader to GdkPixbufLoader*

* src/io-png.c: Progressive loading stuff compiles, untested.