wasapisrc: Correctly disable provide-clock

`#ifdef` will, of course, evaluate to 1 in this case. We want `#if`.
diff --git a/sys/wasapi/gstwasapisrc.c b/sys/wasapi/gstwasapisrc.c
index bf52062..c0844f1 100644
--- a/sys/wasapi/gstwasapisrc.c
+++ b/sys/wasapi/gstwasapisrc.c
@@ -89,7 +89,7 @@
 static guint gst_wasapi_src_delay (GstAudioSrc * asrc);
 static void gst_wasapi_src_reset (GstAudioSrc * asrc);
 
-#ifdef DEFAULT_PROVIDE_CLOCK
+#if DEFAULT_PROVIDE_CLOCK
 static GstClockTime gst_wasapi_src_get_time (GstClock * clock,
     gpointer user_data);
 #endif
@@ -165,7 +165,7 @@
 static void
 gst_wasapi_src_init (GstWasapiSrc * self)
 {
-#ifdef DEFAULT_PROVIDE_CLOCK
+#if DEFAULT_PROVIDE_CLOCK
   /* override with a custom clock */
   if (GST_AUDIO_BASE_SRC (self)->clock)
     gst_object_unref (GST_AUDIO_BASE_SRC (self)->clock);
@@ -663,7 +663,7 @@
   GST_OBJECT_UNLOCK (self);
 }
 
-#ifdef DEFAULT_PROVIDE_CLOCK
+#if DEFAULT_PROVIDE_CLOCK
 static GstClockTime
 gst_wasapi_src_get_time (GstClock * clock, gpointer user_data)
 {