tools: Record NSS dependency on symbols file

If a symbol file for either of NSS modules is changed then
subsequent 'make' doesn't regenerate the library, because there
is no implicit dependency between the library and symbols file.
Put an explicit dependency into the Makefile then. Unfortunately,
setting _DEPENDENCIES makes us lose automake's generated
dependencies (see src/Makefile.am:592 for details). But
fortunately, the only dependency we had was _LIBADD variable.
Signed-off-by: NMichal Privoznik <mprivozn@redhat.com>
Reviewed-by: NErik Skultety <eskultet@redhat.com>

tools/Makefile.am

@@ -535,6 +535,10 @@ nss_libnss_libvirt_la_LDFLAGS = \
 nss_libnss_libvirt_la_LIBADD = \
 	nss/libnss_libvirt_impl.la
 
+nss_libnss_libvirt_la_DEPENDENCIES = \
+	$(nss_libnss_libvirt_la_LIBADD) \
+	$(LIBVIRT_NSS_SYMBOL_FILE)
+
 noinst_LTLIBRARIES += nss/libnss_libvirt_guest_impl.la
 nss_libnss_libvirt_guest_impl_la_SOURCES = \
 	$(LIBVIRT_NSS_SOURCES) \
@@ -567,6 +571,10 @@ nss_libnss_libvirt_guest_la_LDFLAGS = \
 nss_libnss_libvirt_guest_la_LIBADD = \
 	nss/libnss_libvirt_guest_impl.la
 
+nss_libnss_libvirt_guest_la_DEPENDENCIES = \
+	$(nss_libnss_libvirt_guest_la_LIBADD) \
+	$(LIBVIRT_GUEST_NSS_SYMBOL_FILE)
+
 lib_LTLIBRARIES = \
 	nss/libnss_libvirt.la \
 	nss/libnss_libvirt_guest.la