[PATCH] Improve CLANG support

Hi all,
  the attached patch partly fixes CLANG support for Trunk.
There are a couple spots where things don't fly however:
- GnuRegex.c : when it is built, some macros it has expand to if
((foo==bar)) {} . Clang barfs on the double parentheses when Werror is
used
- strtoll: Building with -std=c++0x makes strtoll unavailable for some
reason. What is really puzzling is that autoconf detects is as
working, and so the bundled implementation is not built. Without the
-std flag, the build is successful.

-- 
    /kinkie