package/Makefile.in: pass --enable-ipv6 to autotargets configure when enabled

Some packages don't automatically enable IPv6 support if not configured
with --disable-ipv6, or use AC_TRY_RUN which doesn't work when cross
compiling (like curl), so explicitly configure with --enable-ipv6.

Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>

package/Makefile.in

@@ -279,7 +279,9 @@ ifneq ($(BR2_HAVE_DOCUMENTATION),y)
 DISABLE_DOCUMENTATION=--disable-gtk-doc
 endif
 
-ifneq ($(BR2_INET_IPV6),y)
+ifeq ($(BR2_INET_IPV6),y)
+DISABLE_IPV6= --enable-ipv6
+else
 DISABLE_IPV6= --disable-ipv6
 endif