os400: update chkstrings.c

Compensate changes for recent changes to urldata.h to reclassify
STRING_AWS_SIGV4.

Fixes #11132
Closes #11133

packages/OS400/chkstrings.c

@@ -37,8 +37,8 @@
  * made, the EXPECTED_STRING_LASTZEROTERMINATED/EXPECTED_STRING_LAST
  * values can be updated to match the latest enum values in urldata.h.
  */
-#define EXPECTED_STRING_LASTZEROTERMINATED  (STRING_SSL_EC_CURVES + 1)
-#define EXPECTED_STRING_LAST                (STRING_AWS_SIGV4 + 1)
+#define EXPECTED_STRING_LASTZEROTERMINATED  (STRING_AWS_SIGV4 + 1)
+#define EXPECTED_STRING_LAST                (STRING_COPYPOSTFIELDS + 1)
 
 int main(int argc, char *argv[])
 {