pgsql: Rewrite pg_regress as a C program instead of a shell script.

Log Message:
-----------
Rewrite pg_regress as a C program instead of a shell script.
This allows it to be used on Windows without installing mingw
(though you do still need 'diff'), and opens the door to future
improvements such as message localization.
Magnus Hagander and Tom Lane.

Modified Files:
--------------
    pgsql/doc:
        FAQ_HPUX (r1.13 -> r1.14)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/FAQ_HPUX.diff?r1=1.13&r2=1.14)
    pgsql/doc/src/sgml:
        regress.sgml (r1.52 -> r1.53)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/regress.sgml.diff?r1=1.52&r2=1.53)
    pgsql/src/makefiles:
        pgxs.mk (r1.7 -> r1.8)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/makefiles/pgxs.mk.diff?r1=1.7&r2=1.8)
    pgsql/src/pl/plperl:
        GNUmakefile (r1.26 -> r1.27)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/pl/plperl/GNUmakefile.diff?r1=1.26&r2=1.27)
    pgsql/src/pl/plpython:
        Makefile (r1.24 -> r1.25)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/pl/plpython/Makefile.diff?r1=1.24&r2=1.25)
    pgsql/src/pl/tcl:
        Makefile (r1.48 -> r1.49)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/pl/tcl/Makefile.diff?r1=1.48&r2=1.49)
    pgsql/src/test/regress:
        GNUmakefile (r1.57 -> r1.58)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/GNUmakefile.diff?r1=1.57&r2=1.58)
        Makefile (r1.13 -> r1.14)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/Makefile.diff?r1=1.13&r2=1.14)

Added Files:
-----------
    pgsql/src/test/regress:
        pg_regress.c (r1.1)

(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/pg_regress.c?rev=1.1&content-type=text/x-cvsweb-markup)

Removed Files:
-------------
    pgsql/src/test/regress:
        pg_regress.sh
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/pg_regress.sh)