libqcdm,reset: fix warnings with -Wsign-compare

reset.c: In function ‘print_buf’:
  reset.c:47:19: warning: comparison of integer expressions of different signedness: ‘int’ and ‘size_t’ {aka ‘long unsigned int’} [-Wsign-compare]
     47 |     for (i = 0; i < len; i++) {
        |                   ^
  reset.c: In function ‘qcdm_wait_reply’:
  reset.c:168:20: warning: comparison of integer expressions of different signedness: ‘int’ and ‘long unsigned int’ [-Wsign-compare]
    168 |     } while (total < sizeof (readbuf));
        |                    ^

libqcdm/tests/reset.c

@@ -37,7 +37,7 @@ static int debug = 0;
 static void
 print_buf (const char *detail, const char *buf, size_t len)
 {
-    int i = 0, z;
+    unsigned int i, z;
     qcdmbool newline = FALSE;
     char tmp[500];
     uint32_t flen;
@@ -121,7 +121,7 @@ qcdm_wait_reply (int fd, char *buf, size_t len)
     struct timeval timeout = { 1, 0 };
     char readbuf[1024];
     ssize_t bytes_read;
-    int total = 0, retries = 0;
+    unsigned int total = 0, retries = 0;
     size_t decap_len = 0;
 
     FD_ZERO (&in);