swresample: allow double precision beta value for the Kaiser window

Kaiser windows inherently don't require beta to be an integer. This was
an arbitrary restriction. Moreover, soxr does not require it, and in
fact often estimates beta to a non-integral value.

Thus, this patch allows greater flexibility for swresample clients.
Micro version is updated.

Reviewed-by: Derek Buitenhuis <derek.buitenhuis@gmail.com>
Reviewed-by: Michael Niedermayer <michael@niedermayer.cc>
Signed-off-by: Ganesh Ajjanagadde <gajjanagadde@gmail.com>

libswresample/resample.h

@@ -44,7 +44,7 @@ typedef struct ResampleContext {
     int phase_mask;
     int linear;
     enum SwrFilterType filter_type;
-    int kaiser_beta;
+    double kaiser_beta;
     double factor;
     enum AVSampleFormat format;
     int felem_size;