sbcenc: Fix build warnings

This fixes the following warnings:

In file included from /usr/include/stdio.h:894,
         from src/sbcenc.c:30:
In function ‘fprintf’,
  inlined from ‘encode’ at src/sbcenc.c:160:3,
  inlined from ‘main’ at src/sbcenc.c:329:3:
/usr/include/bits/stdio2.h:105:10: error: ‘srate’ may be
used uninitialized [-Werror=maybe-uninitialized]
 105 |  return __fprintf_chk (__stream, __USE_FORTIFY_LEVEL - 1, __fmt,
   |     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 106 |             __va_arg_pack ());
   |             ~~~~~~~~~~~~~~~~~
src/sbcenc.c: In function ‘main’:
src/sbcenc.c:54:23: note: ‘srate’ was declared here
  54 |     int fd, size, srate, codesize, nframes;
   |            ^~~~~
cc1: all warnings being treated as errors

0 files changed, 0 insertions, 0 deletions