build: fix build --without-network

bridge_driver.h: silence gcc warnings:
statement with no effect [-Wunused-value]
unused variable 'net' [-Wunused-variable]

virdrivermoduletest.c: don't require network driver module
if it hasn't been built.

src/network/bridge_driver.h

@@ -53,8 +53,8 @@ int networkBuildDhcpDaemonCommandLine(virNetworkObjPtr network,
 # else
 /* Define no-op replacements that don't drag in any link dependencies.  */
 #  define networkAllocateActualDevice(iface) 0
-#  define networkNotifyActualDevice(iface) 0
-#  define networkReleaseActualDevice(iface) 0
+#  define networkNotifyActualDevice(iface) (iface=iface, 0)
+#  define networkReleaseActualDevice(iface) (iface=iface, 0)
 #  define networkGetNetworkAddress(netname, netaddr) (-2)
 #  define networkBuildDhcpDaemonCommandLine(network, cmdout, pidfile, dctx) 0
 # endif

tests/virdrivermoduletest.c

@@ -65,7 +65,10 @@ mymain(void)
     virDriverModuleInitialize(abs_builddir "/../src/.libs");
 
 #ifdef WITH_NETWORK
+# define USE_NETWORK "network"
     TEST("network", NULL);
+#else
+# define USE_NETWORK NULL
 #endif
 #ifdef WITH_STORAGE
     TEST("storage", NULL);
@@ -83,10 +86,10 @@ mymain(void)
     TEST("interface", NULL);
 #endif
 #ifdef WITH_QEMU
-    TEST("qemu", "network");
+    TEST("qemu", USE_NETWORK);
 #endif
 #ifdef WITH_LXC
-    TEST("lxc", "network");
+    TEST("lxc", USE_NETWORK);
 #endif
 #ifdef WITH_UML
     TEST("uml", NULL);