package/dhcp: add host-gawk optional dependency

On hosts where gawk is not available, it is not possible to build the package with server option (BR2_PACKAGE_DHCP_SERVER).
The build goes through without errors but the binaries are not created and installed. The reason is that autotools cannot find gawk.

---
 package/dhcp/dhcp.mk | 1 +
 1 file changed, 1 insertion(+)

index 988c7792dc..8d7157f357 100644
@@ -55,6 +55,7 @@ define DHCP_INSTALL_LIBS
 endef
 
 ifeq ($(BR2_PACKAGE_DHCP_SERVER),y)
+DHCP_DEPENDENCIES += host-gawk
 define DHCP_INSTALL_CTL_LIBS
 	$(MAKE) -C $(@D)/dhcpctl install-exec DESTDIR=$(TARGET_DIR)
 endef

2.30.0