Part of Bug #258005 --> get rid of the empty string initialization of buf

that was part of the original patch.

mailnews/compose/src/nsMsgCompUtils.cpp

@@ -821,7 +821,7 @@ mime_generate_attachment_headers (const char *type,
 {
   nsresult rv;
 
-  nsCString buf("");
+  nsCString buf;
 
   NS_ASSERTION (encoding, "null encoding");