THRIFT-2849: spelling errors fixed using codespell tool

Client: All
Patch: Anatol Pomozov

This closes #281
diff --git a/contrib/fb303/TClientInfo.h b/contrib/fb303/TClientInfo.h
index d0a9770..6668c19 100644
--- a/contrib/fb303/TClientInfo.h
+++ b/contrib/fb303/TClientInfo.h
@@ -192,7 +192,7 @@
 
   /**
    * Return as string the thrift call either currently being processed or
-   * most recently processed if the connection is still open for additonal
+   * most recently processed if the connection is still open for additional
    * calls.  Returns NULL if a call hasn't been made yet or processing
    * has ended.
    */