Add a workaround and fixes PR pkg/50284 forcing building webkit-gtk with

-march=i586 in order to avoid on i386 the "-latomic" flag when linking
libwebkit2gtk-4.0.so.

Bump PKGREVISION.

Thanks joerg@, jperkin@ and tnn@ for various suggestions.

www/webkit-gtk/Makefile

@@ -1,7 +1,8 @@
-# $NetBSD: Makefile,v 1.98 2015/09/26 10:16:37 leot Exp $
+# $NetBSD: Makefile,v 1.99 2015/10/05 16:25:30 leot Exp $
 
 DISTNAME=	webkitgtk-2.10.0
 PKGNAME=	${DISTNAME:S/webkitgtk/webkit-gtk/}
+PKGREVISION=	1
 CATEGORIES=	www
 MASTER_SITES=	http://www.webkitgtk.org/releases/
 EXTRACT_SUFX=	.tar.xz

www/webkit-gtk/hacks.mk

@@ -0,0 +1,16 @@
+# $NetBSD: hacks.mk,v 1.1 2015/10/05 16:25:30 leot Exp $
+
+.if !defined(WEBKIT_GTK_HACKS_MK)
+WEBKIT_GTK_HACKS_MK=	defined
+
+# [Sat Oct  3 16:44:53 CEST 2015 : leot]
+# On i386 archs -latomic is added during the build phase when linking
+# libwebkit2gtk-4.0.so for atomic operations.
+# Forcing -march=i586 (or better) avoids that (i[56]86 provide required
+# 64-bit compare-and-swap instruction).
+.if ${MACHINE_ARCH} == "i386"
+PKG_HACKS+=	i386-atomicops
+CXXFLAGS+=	-march=i586
+.endif
+
+.endif	# WEBKIT_GTK_HACKS_MK