[Boost-build] PCH changes

From: Vladimir Prus (ghost_at_[hidden])
Date: 2006-10-07 06:09:28

I've just committed a large change to PCH handling. The bulk of this change 
was done by Ilya Sokolov and adds PCH support for the gcc toolset. Also, now 
instead of 'pch' rule, there are 'cpp-pch' and 'c-pch' rules -- which 
explicitly indicate the language of the header.

I've also took the change to address the need to use 'cast pchheader' -- now 
this should not be required, and won't work anyway.

I've also committed automated test for PCH functionality, which works on gcc.

I was no able to test with msvc, although I carefully looked at command lines, 
and they look correct. I'd appreciate if somebody test this on msvc, and try 
running the 'pch.py' test as well.

Finally, an example 'pch' was added to the example directory.

- Volodya

-- 
Vladimir Prus
http://vladimir_prus.blogspot.com
Boost.Build V2: http://boost.org/boost-build2