only link to -lipq if needed

(This used to be ctdb commit 7c378d881e37db0f14e07ccba19fde1f9f4f0831)

ctdb/Makefile.in

@@ -23,6 +23,8 @@ POPT_LIBS = @POPT_LIBS@
 POPT_CFLAGS = @POPT_CFLAGS@
 POPT_OBJ = @POPT_OBJ@
 
+IPQ_LIBS = @IPQ_LIBS@
+
 CFLAGS=-g -I$(srcdir)/include -Iinclude -Ilib -Ilib/util -I$(srcdir) \
        -I@tallocdir@ -I@tdbdir@/include -I@libreplacedir@ \
 	-DVARDIR=\"$(localstatedir)\" -DETCDIR=\"$(etcdir)\" \
@@ -86,7 +88,7 @@ bin/scsi_io: $(CTDB_CLIENT_OBJ) utils/scsi_io/scsi_io.o
 
 bin/ctdb_ipmux: $(CTDB_CLIENT_OBJ) utils/ipmux/ipmux.o 
 	@echo Linking $@
-	@$(CC) $(CFLAGS) -o $@ utils/ipmux/ipmux.o $(CTDB_CLIENT_OBJ) $(LIB_FLAGS) -lipq
+	@$(CC) $(CFLAGS) -o $@ utils/ipmux/ipmux.o $(CTDB_CLIENT_OBJ) $(LIB_FLAGS) $(IPQ_LIBS)
 
 bin/ctdb: $(CTDB_CLIENT_OBJ) tools/ctdb.o 
 	@echo Linking $@

ctdb/configure.ac

@@ -49,6 +49,12 @@ m4_include(ib/config.m4)
 
 AC_CHECK_HEADERS(libipq.h linux/netfilter.h)
 
+IPQ_LIBS=""
+if test x"$ac_cv_header_libipq_h" = x"yes"; then
+   IPQ_LIBS="-lipq"
+fi
+AC_SUBST(IPQ_LIBS)
+
 AC_CHECK_HEADERS(sched.h)
 AC_CHECK_FUNCS(sched_setscheduler)