pgsql: Fix inclusions of readline/editline header files so that we only

Log Message:
-----------
Fix inclusions of readline/editline header files so that we only attempt to
#include the version of history.h that is in the same directory as the
readline.h we are using. This avoids problems in some scenarios where both
readline and editline are installed. Report and patch by Zdenek Kotala.

Tags:
----
REL8_2_STABLE

Modified Files:
--------------
pgsql/src/bin/psql:
input.h (r1.28 -> r1.28.2.1)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/bin/psql/input.h?r1=1.28&r2=1.28.2.1)