use parenthesis around value

Originally committed as revision 5866 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavformat/mxf.c

@@ -165,7 +165,7 @@ static const uint8_t mxf_essence_element_key[]             = { 0x06,0x0e,0x2b,0x
 #define IS_KLV_KEY(x, y) (!memcmp(x, y, sizeof(y)))
 
 #define PRINT_KEY(x) dprintf("%02X %02X %02X %02X %02X %02X %02X %02X %02X %02X %02X %02X %02X %02X %02X %02X\n", \
-                             x[0], x[1], x[2], x[3], x[4], x[5], x[6], x[7], x[8], x[9], x[10], x[11], x[12], x[13], x[14], x[15])
+                             (x)[0], (x)[1], (x)[2], (x)[3], (x)[4], (x)[5], (x)[6], (x)[7], (x)[8], (x)[9], (x)[10], (x)[11], (x)[12], (x)[13], (x)[14], (x)[15])
 
 static int64_t klv_decode_ber_length(ByteIOContext *pb)
 {