zpool: import: use realloc for realloc, remove strtok

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: John Kennedy <john.kennedy@delphix.com>
Signed-off-by: Ahelenia Ziemiańska <nabijaczleweli@nabijaczleweli.xyz>
Closes #12094

cmd/zpool/zpool_util.h

@@ -39,6 +39,7 @@ extern "C" {
  * Basic utility functions
  */
 void *safe_malloc(size_t);
+void *safe_realloc(void *, size_t);
 void zpool_no_memory(void);
 uint_t num_logs(nvlist_t *nv);
 uint64_t array64_max(uint64_t array[], unsigned int len);