pgsql: Build src/test/regress/README during tarball making like the

Log Message:
-----------
Build src/test/regress/README during tarball making like the other
generated text files.  Fix build of that file, too.

Put the text files in the right place during make dist, so there are no
extra manual steps required anymore.

Modified Files:
--------------
    pgsql:
        GNUmakefile.in (r1.43 -> r1.44)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/GNUmakefile.in.diff?r1=1.43&r2=1.44)
    pgsql/doc/src/sgml:
        Makefile (r1.75 -> r1.76)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/Makefile.diff?r1=1.75&r2=1.76)
        regress.sgml (r1.50 -> r1.51)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/regress.sgml.diff?r1=1.50&r2=1.51)

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