systemd/tests: don't link test-systemd against libNetworkManagerBase

One point of test-systemd is to see whether our internal systemd code can
fully link without external systemd library. In fact, we want all symbols
from the internal systemd code to resolve, because when we link against
an external libsystemd library, we may mix differing APIs, resulting in
subtle bugs.

Currently, it may well be that libNetworkManagerBase.la already links
against libsystemd, which would result in test-systemd to wrongly
succeed resolving all names.

Fix that, by don't link libNetworkManagerBase.la into test-systemd.

src/tests/Makefile.am

@@ -130,7 +130,6 @@ test_systemd_SOURCES = \
 	test-systemd.c
 
 test_systemd_LDADD = \
-	$(top_builddir)/src/libNetworkManagerBase.la \
 	$(top_builddir)/src/libsystemd-nm.la
 
 ####### utils test #######

src/tests/test-systemd.c

@@ -27,6 +27,51 @@
 
 #include "nm-test-utils-core.h"
 
+/*****************************************************************************
+ * Stub implementations of libNetworkManagerBase symbols
+ *****************************************************************************/
+
+gboolean
+nm_utils_get_testing_initialized (void)
+{
+	return TRUE;
+}
+
+void
+_nm_utils_set_testing (NMUtilsTestFlags flags)
+{
+	g_assert_not_reached ();
+}
+
+gint32
+nm_utils_get_monotonic_timestamp_s (void)
+{
+	return 1;
+}
+
+NMLogDomain _nm_logging_enabled_state[_LOGL_N_REAL];
+
+void
+_nm_log_impl (const char *file,
+              guint line,
+              const char *func,
+              NMLogLevel level,
+              NMLogDomain domain,
+              int error,
+              const char *fmt,
+              ...)
+{
+}
+
+gboolean
+nm_logging_setup (const char  *level,
+                  const char  *domains,
+                  char       **bad_domains,
+                  GError     **error)
+{
+	return TRUE;
+}
+
 /*****************************************************************************/
 
 static void