a small patch to the gcc preprocessor

[Chris Moller]

I've attached a small patch to src/gcc/cccp.c that gives the
preprocessor a new directive `#cinclude'.  #cinclude -- "conditional
include" -- includes the specified file if it exists but doesn't cause
an error if the file doesn't exist.  Syntax is the same as the #include
directive.

I've also included a patch to the Changelog.

Patches are against egcs-2.91.57 from cygwin b20.1

Chris Moller
Senior Programmer
BOPS, Inc