Replace int -> uint to avoid signed integer overflow

An example of such an error (should be compiled with DEBUG_SANITIZE):

runtime error: left shift of 1 by 31 places cannot be represented in
type 'int'

Signed-off-by: Rostislav Skudnov <rostislav@tuxera.com>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

miscutils/rx.c

@@ -94,7 +94,7 @@ static int receive(/*int read_fd, */int file_fd)
 		int blockBegin;
 		int blockNo, blockNoOnesCompl;
 		int cksum_or_crc;
-		int expected;
+		unsigned expected;
 		int i, j;
 
 		blockBegin = read_byte(timeout);