include orders

[DJ Delorie]

I've just checked in a big patch to always include winsup.h before
other system headers.  This ensures that we get the right import tags.
I also took the __INSIDE_CYGWIN__ out of Makefile.in as it was being
used for the profiling library also, which was bad.  winsup.h can now
be used in C files as well as C++; and I added it to the few C files
in cygwin1.dll.

So, the new rule is: always include winsup.h before other headers.