calc(*) are now PCHARP functions.

I also fixed five errors that hopefully did not really matter all that
much in calc(*):

o Two instances of data[1] instead of data[pos+1]
o Three instances of data[pos]+1 instead of data[pos+1]

The first error would be triggered if you used '/' in an #if and the
second character of the current cpp work area was '/'.

The second one is probably harmless. Or not, it was in the code for
'&' and '|': basically the detection of && and || there was broken.

However, I think that would be handled by the calling order of the
calc* functions.

Anyway, cpp.o is now less than 100k, about 45% of its original size
(OSX 64-bit).
low*_cpp now uses PCHARP.

Shaves of about 50% of the remaining code size.  Now down to about
50Kb, which seems more reasonable than 200k.

There is still a lot of code duplication, though, like the places that
insert the current file as a #line, the code that handles quoted
newlines etc.

But it is better.

I also removed macros that were only used once and inlined them.