tests: name the renegotiation_info extension and widen two skip messages

The ClientHello builder wrote the renegotiation_info extension type as a
conditional whose two branches were the same constant, which is a constant
expression some -Wextra builds reject and which hid what 0xFF01 is. It is
TLSX_RENEGOTIATION_INFO; use that.

The CRL and OCSP skip stubs are guarded on their feature macro plus certs plus
not-WOLFCRYPT_ONLY. Their printed messages already said so; the #else comments
still named only the feature macro, so a reader chasing a skip saw the wrong
reason.

No coverage change: tls_core 810/1748 and revocation 28/47 + 31/48 both
re-measured identical, gates green.

tests/unit-mcdc/test_crl_whitebox.c

@@ -523,7 +523,7 @@ done:
     return 0;   /* always 0: a non-zero exit discards the variant */
 }
 
-#else /* !HAVE_CRL */
+#else /* not (HAVE_CRL && certs && !WOLFCRYPT_ONLY) */
 
 int main(void)
 {

tests/unit-mcdc/test_internal_clienthello_whitebox.c

@@ -169,7 +169,7 @@ static void wb_build(Frame* f, const Hello* h, int dtls, const WOLFSSL* ssl)
         Frame ext;
         fr_reset(&ext);
         if (h->extReneg) {
-            fr_u16(&ext, HELLO_EXT_SIG_ALGO == 0 ? 0xFF01 : 0xFF01);
+            fr_u16(&ext, TLSX_RENEGOTIATION_INFO);
             fr_u16(&ext, 1);
             fr_u8(&ext, 0);                    /* empty renegotiated_connection */
         }

tests/unit-mcdc/test_ocsp_whitebox.c

@@ -650,7 +650,7 @@ done:
     return 0;   /* always 0: a non-zero exit discards the variant */
 }
 
-#else /* !HAVE_OCSP */
+#else /* not (HAVE_OCSP && certs && !WOLFCRYPT_ONLY) */
 
 int main(void)
 {