fakesrc, identity, fakesink: do not generate last-message updates by default

Default to not creating lots of overhead by doing a couple of
g_strdup_printf()/g_free() per buffer or event just to generate
a last-message update that rarely anyone listens to. This means
that you need to enable silent=true explicitly in order to get
last-message dumps in gst-launch -v now. On the upside, people
won't inadvertently end up benchmarking g_strdup_printf()
performance instead of gstreamer data handling performance any
more.

Maybe the silent property should be renamed to enable-last-message
or something like that?

plugins/elements/gstfakesink.c

@@ -61,7 +61,7 @@ enum
 #define DEFAULT_SYNC FALSE
 
 #define DEFAULT_STATE_ERROR FAKE_SINK_STATE_ERROR_NONE
-#define DEFAULT_SILENT FALSE
+#define DEFAULT_SILENT TRUE
 #define DEFAULT_DUMP FALSE
 #define DEFAULT_SIGNAL_HANDOFFS FALSE
 #define DEFAULT_LAST_MESSAGE NULL

plugins/elements/gstfakesrc.c

@@ -81,7 +81,7 @@ enum
 #define DEFAULT_PATTERN         NULL
 #define DEFAULT_EOS             FALSE
 #define DEFAULT_SIGNAL_HANDOFFS FALSE
-#define DEFAULT_SILENT          FALSE
+#define DEFAULT_SILENT          TRUE
 #define DEFAULT_DUMP            FALSE
 #define DEFAULT_PARENTSIZE      4096*10
 #define DEFAULT_CAN_ACTIVATE_PULL TRUE

plugins/elements/gstidentity.c

@@ -64,7 +64,7 @@ enum
 #define DEFAULT_ERROR_AFTER             -1
 #define DEFAULT_DROP_PROBABILITY        0.0
 #define DEFAULT_DATARATE                0
-#define DEFAULT_SILENT                  FALSE
+#define DEFAULT_SILENT                  TRUE
 #define DEFAULT_SINGLE_SEGMENT          FALSE
 #define DEFAULT_DUMP                    FALSE
 #define DEFAULT_SYNC                    FALSE