FILS: Add 'GET_CAPABILITY fils' for runtime check

This can be used to check whether the running wpa_supplicant version was
built with CONFIG_FILS=y.

Signed-off-by: Jouni Malinen <jouni@qca.qualcomm.com>

wpa_supplicant/ctrl_iface.c

@@ -4006,6 +4006,15 @@ static int wpa_supplicant_ctrl_iface_get_capability(
 	}
 #endif /* CONFIG_ACS */
 
+#ifdef CONFIG_FILS
+	if (os_strcmp(field, "fils") == 0) {
+		res = os_snprintf(buf, buflen, "FILS");
+		if (os_snprintf_error(buflen, res))
+			return -1;
+		return res;
+	}
+#endif /* CONFIG_FILS */
+
 	wpa_printf(MSG_DEBUG, "CTRL_IFACE: Unknown GET_CAPABILITY field '%s'",
 		   field);