Unbreak webp-pixbuf-loader for big-endian platforms

The patch calls le32toh in <endian.h>, because OpenBSD doesn't have
<byteswap.h>.  This prevents a fatal error on BE_ARCHS when byteswap.h
didn't exist.

ok jsg@ jca@

graphics/webp-pixbuf-loader/Makefile

@@ -3,6 +3,7 @@ COMMENT=		WebP GDK Pixbuf Loader library
 GH_ACCOUNT=		aruiz
 GH_PROJECT=		webp-pixbuf-loader
 GH_TAGNAME=		0.0.6
+REVISION=		0
 
 CATEGORIES=		graphics
 

graphics/webp-pixbuf-loader/patches/patch-io-webp_c

@@ -0,0 +1,27 @@
+Use <endian.h>; OpenBSD doesn't have <byteswap.h>.
+
+Index: io-webp.c
+--- io-webp.c.orig
++++ io-webp.c
+@@ -12,9 +12,7 @@
+ 
+ #include "io-webp.h"
+ 
+-#if __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
+-#include <byteswap.h>
+-#endif
++#include <endian.h>
+ 
+ #define  IMAGE_READ_BUFFER_SIZE 65535
+ 
+@@ -278,9 +276,7 @@ gdk_pixbuf__webp_anim_load_increment (gpointer      co
+                 /* The next 4 bytes give the size of the webp container less the 8 byte header. */
+                 uint32_t anim_size = *(uint32_t *) (buf + 4); /* gives file size not counting the first 8 bytes. */
+ 
+-                #if __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
+-		anim_size = bswap_32(anim_size);
+-                #endif
++		anim_size = le32toh(anim_size);
+ 
+                 uint32_t file_size = anim_size + 8;
+                 if (file_size < size) {