cppcheck: resolve double free

The double free reported for the realloc() failure branch is a
false positive.  It should be resolved in cppcheck 2.4 but for
the benefit of older versions we supress the warning.

    https://trac.cppcheck.net/ticket/9292

Reviewed-by: Ryan Moeller <ryan@ixsystems.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #11508

lib/libefi/rdwr_efi.c

@@ -468,6 +468,7 @@ efi_alloc_and_read(int fd, struct dk_gpt **vtoc)
 		    (int) sizeof (struct dk_part) * (vptr->efi_nparts - 1);
 		nparts = vptr->efi_nparts;
 		if ((tmp = realloc(vptr, length)) == NULL) {
+			/* cppcheck-suppress doubleFree */
 			free(vptr);
 			*vtoc = NULL;
 			return (VT_ERROR);