archive-tar: mark RECORDSIZE/BLOCKSIZE as unsigned

They really are unsigned, and we are using e.g. BLOCKSIZE as `size_t`
parameter to pass to `write_or_die()`.

Signed-off-by: Johannes Schindelin <[email protected]>

Author: dscho

archive-tar.c

@@ -9,7 +9,7 @@
 #include "streaming.h"
 #include "run-command.h"
 
-#define RECORDSIZE	(512)
+#define RECORDSIZE	(512u)
 #define BLOCKSIZE	(RECORDSIZE * 20)
 
 static char block[BLOCKSIZE];