This restores the Linux behavior to what it was in PG 7.0 and 7.1, and
causes other platforms to agree. (Other well-tested platforms like HPUX
were doing it this way already.) Per pghackers discussion over the past
month or so.
are now separate files "postgres.h" and "postgres_fe.h", which are meant
to be the primary include files for backend .c files and frontend .c files
respectively. By default, only include files meant for frontend use are
installed into the installation include directory. There is a new make
target 'make install-all-headers' that adds the whole content of the
src/include tree to the installed fileset, for use by people who want to
develop server-side code without keeping the complete source tree on hand.
Cleaned up a whole lot of crufty and inconsistent header inclusions.
