Fix Ximian bug #12125; merged from gdk-pixbuf stable.

Fix Ximian bug #12125; merged from gdk-pixbuf stable.

2001-11-21  Federico Mena Quintero  <federico@ximian.com>

	Fix Ximian bug #12125; merged from gdk-pixbuf stable.

	* gdk-pixbuf/io-bmp.c (gdk_pixbuf__bmp_image_load_increment): Use
	a simple state machine instead of a scary if/else chain.
	(DecodeHeader): Set the reading state.
	(DecodeColormap): Set the reading state.
	(decode_bitmasks): New function, decodes the bitmasks for
	BI_BITFIELDS coding.
	(OneLine32): Handle BI_BITFIELDS coding.
	(OneLine16): Likewise.