escape130: The minimum read in and after decode_skip_count() is 4 bits.

Thus we can check for 4 being available.
If the next block is skiped we need 4 bits to encode the skip. If the
next block is not skiped then we need 1 bit for the skip code and
at least 3 bits for the block.
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavcodec/escape130.c

@@ -69,7 +69,7 @@ static unsigned decode_skip_count(GetBitContext* gb) {
     unsigned value;
     // This function reads a maximum of 27 bits,
     // which is within the padding space
-    if (!can_safely_read(gb, 1))
+    if (!can_safely_read(gb, 1+3))
         return -1;
 
     value = get_bits1(gb);