Add support for --enable-exampledir to specify where to place example
files, defaulting to sysconfdir (matching previous behavior).

This is needed to support (cleanly) NetBSD pkgsrc, which requires that
example config files go in $(prefix)/share/examples/pkgname, rather
than in $(prefix)/etc/pkgname.
diff --git a/ripd/Makefile.am b/ripd/Makefile.am
index ab63134..505f7b7 100644
--- a/ripd/Makefile.am
+++ b/ripd/Makefile.am
@@ -19,7 +19,8 @@
 
 ripd_LDADD = -L../lib -lzebra @LIBCAP@
 
-dist_sysconf_DATA = ripd.conf.sample
+examplesdir = $(exampledir)
+dist_examples_DATA = ripd.conf.sample
 
 EXTRA_DIST = RIPv2-MIB.txt