swr: fix compilation failure with old versions of gcc.

gcc 4.4 did not like the way i used typedefs

Idea-by: beastd
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libswresample/swresample_internal.h

@@ -32,7 +32,7 @@ typedef struct AudioData{
     int planar;                 ///< 1 if planar audio, 0 otherwise
 } AudioData;
 
-typedef struct SwrContext {
+struct SwrContext {
     const AVClass *av_class;                        ///< AVClass used for AVOption and av_log()
     int log_level_offset;                           ///< logging level offset
     void *log_ctx;                                  ///< parent logging context
@@ -75,7 +75,7 @@ typedef struct SwrContext {
     uint8_t matrix_ch[SWR_CH_MAX][SWR_CH_MAX+1];    ///< Lists of input channels per output channel that have non zero rematrixing coefficients
 
     /* TODO: callbacks for ASM optimizations */
-}SwrContext;
+};
 
 struct ResampleContext *swri_resample_init(struct ResampleContext *, int out_rate, int in_rate, int filter_size, int phase_shift, int linear, double cutoff);
 void swri_resample_free(struct ResampleContext **c);