expect instability in cpplib for the next week or two

[Zack Weinberg]

I'm doing some major rewriting of parts of cpplib.  This means that
bugs like -U causing an internal error may not get fixed very fast.
It also means that there are likely to be more bugs than normal.

If the preprocessor is preventing you from getting work done, you can
always use --disable-cpplib to go back to the old preprocessor.

On the up side, when the rewrites are done cpp should be less fragile
and significantly faster.  It will also be easier to integrate with
the C and C++ front ends, which in turn will give us more performance
benefits and some ease of use improvements (like column numbers).

zw