fft: Mark one function as const and add notes that the structs should be private in 0.11

gst-libs/gst/fft/gstfft.h

@@ -44,6 +44,6 @@ typedef enum
 
 /* Functions */
 
-gint gst_fft_next_fast_length (gint n);
+gint gst_fft_next_fast_length (gint n) G_GNUC_CONST;
 
 #endif /* __GST_FFT_H__ */

gst-libs/gst/fft/gstfftf32.h

@@ -28,6 +28,9 @@
 typedef struct _GstFFTF32 GstFFTF32;
 typedef struct _GstFFTF32Complex GstFFTF32Complex;
 
+/* FIXME 0.11: Move the struct definition to the sources,
+ *             there's no reason to have it public.
+ */
 /**
  * GstFFTF32:
  *

gst-libs/gst/fft/gstfftf64.h

@@ -28,6 +28,9 @@
 typedef struct _GstFFTF64 GstFFTF64;
 typedef struct _GstFFTF64Complex GstFFTF64Complex;
 
+/* FIXME 0.11: Move the struct definition to the sources,
+ *             there's no reason to have it public.
+ */
 /**
  * GstFFTF64:
  *

gst-libs/gst/fft/gstffts16.h

@@ -28,6 +28,9 @@
 typedef struct _GstFFTS16 GstFFTS16;
 typedef struct _GstFFTS16Complex GstFFTS16Complex;
 
+/* FIXME 0.11: Move the struct definition to the sources,
+ *             there's no reason to have it public.
+ */
 /**
  * GstFFTS16:
  *

gst-libs/gst/fft/gstffts32.h

@@ -28,6 +28,9 @@
 typedef struct _GstFFTS32 GstFFTS32;
 typedef struct _GstFFTS32Complex GstFFTS32Complex;
 
+/* FIXME 0.11: Move the struct definition to the sources,
+ *             there's no reason to have it public.
+ */
 /**
  * GstFFTS32:
  *