loas_probe: make buffer pointers const

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

libavformat/loasdec.c

@@ -29,10 +29,10 @@ static int loas_probe(AVProbeData *p)
 {
     int max_frames = 0, first_frames = 0;
     int fsize, frames;
-    uint8_t *buf0 = p->buf;
-    uint8_t *buf2;
-    uint8_t *buf;
-    uint8_t *end = buf0 + p->buf_size - 3;
+    const uint8_t *buf0 = p->buf;
+    const uint8_t *buf2;
+    const uint8_t *buf;
+    const uint8_t *end = buf0 + p->buf_size - 3;
     buf = buf0;
 
     for(; buf < end; buf= buf2+1) {