Fix keyboard-interactive without TERM

Keyboard-interactive was unusable in builds with
WOLFSSH_KEYBOARD_INTERACTIVE but no WOLFSSH_TERM, in two ways.

- ClientFreeBuffers declared 'entry' under TERM && KBI but used it
  under KBI alone, so KBI-without-TERM failed to compile; widen the
  declaration guard to match the use
- ClientUserAuth's keyboard-interactive branch is guarded on
  TERM && KBI, so without TERM a keyboard-interactive request fell
  past every branch and returned the initial WOLFSSH_USERAUTH_SUCCESS
  with no responses populated. There is no terminal to prompt on, so
  answer WOLFSSH_USERAUTH_FAILURE instead of claiming success.

examples/client/common.c

@@ -606,6 +606,12 @@ int ClientUserAuth(byte authType,
             }
         }
     }
+#elif defined(WOLFSSH_KEYBOARD_INTERACTIVE)
+    else if (authType == WOLFSSH_USERAUTH_KEYBOARD) {
+        /* Without a terminal there is nowhere to prompt for the responses, so
+         * this build cannot answer a keyboard-interactive request. */
+        ret = WOLFSSH_USERAUTH_FAILURE;
+    }
 #endif
     return ret;
 }
@@ -1118,7 +1124,7 @@ int ClientLoadCA(WOLFSSH_CTX* ctx, const char* caCert)
 void ClientFreeBuffers(const char* pubKeyName, const char* privKeyName,
         void* heap)
 {
-#if defined(WOLFSSH_TERM) && defined(WOLFSSH_KEYBOARD_INTERACTIVE)
+#ifdef WOLFSSH_KEYBOARD_INTERACTIVE
     word32 entry;
 #endif
 #ifdef WOLFSSH_TPM