dtmf: Update dtmfdetect to make it MSVC friendly

https://bugzilla.gnome.org/show_bug.cgi?id=602465

gst/dtmf/tone_detect.c

@@ -32,7 +32,6 @@
 */
 
 #include <math.h>
-#include <stdint.h>
 #include <string.h>
 #include <stdio.h>
 #include <time.h>

gst/dtmf/tone_detect.h

@@ -30,6 +30,11 @@
         detriment.
 */
 
+#ifndef __TONE_DETECT_H__
+#define __TONE_DETECT_H__
+
+#include <stdint.h>
+
 typedef struct
 {
     float v2;
@@ -83,4 +88,6 @@ int zap_dtmf_get (dtmf_detect_state_t *s,
               char *buf,
               int max);
 
+#endif /* __TONE_DETECT_H__ */
+
 /*- End of file ------------------------------------------------------------*/