pgsql: This patch changes the use of varargs.h to stdarg.h as required

Log Message:
-----------
This patch changes the use of varargs.h to stdarg.h as
required by modern versions of GCC.

Niels Breet

Modified Files:
--------------
pgsql/src/tools/entab:
halt.c (r1.5 -> r1.6)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/tools/entab/halt.c.diff?r1=1.5&r2=1.6)