allow users to build with !(gcc && gmake) from CVS by adding the use of
the $AUTOMAKE_FLAGS environment variable.  (gcc && gmake) users will notice
no difference.
- Added HACKING file to all four projects that gives a brief description on
how to build the source from CVS.  Mainly: "cvs update.  ./autogen.sh.
./configure.  make.  Oongowa."


git-svn-id: http://svn.xiph.org/trunk/ao@1914 0101bb08-14d6-0310-b084-bc0e0c8e3800