pkgconf: fix upstream URL

The upstream URL has changed to
http://rabbit.dereferenced.org/~nenolod/distfiles/, updated the
Buildroot pkgconf package accordingly.

Fixes #6638.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Reported-by: <masrur.macece@gmail.com>
Cc: <masrur.macece@gmail.com>

package/pkgconf/pkgconf.mk

@@ -5,7 +5,7 @@
 ################################################################################
 
 PKGCONF_VERSION = 0.8.9
-PKGCONF_SITE = http://tortois.es/~nenolod/distfiles
+PKGCONF_SITE = http://rabbit.dereferenced.org/~nenolod/distfiles/
 PKGCONF_SOURCE = pkgconf-$(PKGCONF_VERSION).tar.bz2
 PKGCONF_LICENSE = pkgconf license
 PKGCONF_LICENSE_FILES = COPYING