[GCC-XML] -fxml syntax updated

[Brad King]

Hello, all:

I have updated the extension to provide the following syntax for dumping
xml:

g++ -fxml=filename -fsyntax-only source.cxx

This will dump the translation unit from source.cxx to a file called
"filename".  The original "-fxml" flag dumped this output to stdout, and
is no longer available.  The web page has been updated to reflect these
changes.

The repository also now includes a cvs diff with the extension against a
checkout of GCC from this morning.  A bug that caused the extension to
seg-fault when it encountered a nameless function argument has been fixed
as well.

Have fun,
-Brad