Enough users expect the namespace starting with underscore to be safe
for symbols. Change our private namespace from __foo__ to
__?foo?__. Use %defalias to provide backwards compatiblity (by using
%defalias instead of %define, we handle the case properly where the
user changes the value.)
Add a preprocessor directive:
%aliases off
... to disable all smacro aliases and thereby making the namespace
clean.
Finally, fix infinite recursion when seeing %? or %?? due to
paste_tokens(). If we don't paste anything, the expansion is done.
Signed-off-by: H. Peter Anvin <hpa@zytor.com>