[png] Add support for PNG images

Signed-off-by: Michael Brown <mcb30@ipxe.org>

Author: mcb30

src/config/config.c

@@ -200,6 +200,9 @@ REQUIRE_OBJECT ( sdi );
 #ifdef IMAGE_PNM
 REQUIRE_OBJECT ( pnm );
 #endif
+#ifdef IMAGE_PNG
+REQUIRE_OBJECT ( png );
+#endif
 
 /*
  * Drag in all requested commands

src/config/general.h

@@ -104,6 +104,7 @@ FILE_LICENCE ( GPL2_OR_LATER );
 //#define	IMAGE_EFI		/* EFI image support */
 //#define	IMAGE_SDI		/* SDI image support */
 //#define	IMAGE_PNM		/* PNM image support */
+//#define	IMAGE_PNG		/* PNG image support */
 
 /*
  * Command-line commands to include