Move timezone database to share/timezone.

#ifndef HAVE_SYMLINK
#define HAVE_SYMLINK 0
#endif

system headers.

Allow system to find timezone database by pasing pkglibdir into the
binary via a define.

Timezone code backend integration done by Magnus Hagander.

from our code.

<   columns and indexes with many duplicate keys

FreeBSD doesn't add .EXE to links.

Michiel Ephraim

'information_schema' is considered a system schema by various
pg_stat*_*_{tables,sequences} views.

Fabien COELHO

for "aclitem" so that it is not an opaque datatype.

I needed these functions to browse aclitems from user land. I can load
them when necessary, but it seems to me that these accessors for a
backend type belong to the backend, so I submit them.

Fabien Coelho

	-D_REENTRANT -D_THREAD_SAFE -D_POSIX_PTHREAD_SEMANTICS

for all ports.  It can't hurt if they are not supported, but it makes
our job easier for porting.

Should fix Darwin compile and other platforms without mucking with the
thread detection code.

some unused #include directives from bufmgr.c, and clarify comments in
bufmgr.h and buf.h