interface/mmal: Reduce the header bytes alloc in the MMAL examples

The examples read the first 512 bytes of the stream and try stuffing
them into the codec as header bytes.
If running a debug build of MMAL this will fail as the extradata
field of the port format is bigger than MMAL_FORMAT_EXTRADATA_MAX_SIZE

Reduce the header bytes array down to 128bytes to match
MMAL_FORMAT_EXTRADATA_MAX_SIZE.

interface/mmal/test/examples/example_basic_1.c

@@ -33,7 +33,7 @@ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 #define CHECK_STATUS(status, msg) if (status != MMAL_SUCCESS) { fprintf(stderr, msg"\n"); goto error; }
 
-static uint8_t codec_header_bytes[512];
+static uint8_t codec_header_bytes[128];
 static unsigned int codec_header_bytes_size = sizeof(codec_header_bytes);
 
 static FILE *source_file;

interface/mmal/test/examples/example_basic_2.c

@@ -35,7 +35,7 @@ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 #define CHECK_STATUS(status, msg) if (status != MMAL_SUCCESS) { fprintf(stderr, msg"\n"); goto error; }
 
-static uint8_t codec_header_bytes[512];
+static uint8_t codec_header_bytes[128];
 static unsigned int codec_header_bytes_size = sizeof(codec_header_bytes);
 
 static FILE *source_file;