chrony: enable pps support

Chrony has the ability to support PPS. Its enablement is determined
primarily from the existence of `sys/timepps.h`. This file is provided
from the pps-tools package. Adjusting Chrony's Makefile to depend on the
pps-tools package if a developer has included pps-tools as part of a
build. Relates to 2cfc966f431c7c715b3fc11ca0467d47432fca33.

Signed-off-by: James Knight <james.knight@rockwellcollins.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/chrony/chrony.mk

@@ -34,6 +34,12 @@ else
 CHRONY_CONF_OPTS += --disable-readline
 endif
 
+# If pps-tools is available, build it before so the package can use it
+# (HAVE_SYS_TIMEPPS_H).
+ifeq ($(BR2_PACKAGE_PPS_TOOLS),y)
+CHRONY_DEPENDENCIES += pps-tools
+endif
+
 define CHRONY_CONFIGURE_CMDS
 	cd $(@D) && $(TARGET_CONFIGURE_OPTS) ./configure $(CHRONY_CONF_OPTS)
 endef