pgsql-server: Win32 regression fixes: .

Log Message:
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Win32 regression fixes:

. only use the -W flag on pwd for $pkglibdir. All the other paths need
to be seen as MSys type paths, whereas $pkglibdir needs to be expressed
as a genuine windows path.
. run single tests in the background and explicitly wait for them -
solves the problem of the MSys shell not waiting properly for the copy
test to finish.
. use pg_ctl to shut down the test postmaster - no more use of ad hoc
kill programs or the task manager.

Andrew Dunstan

Modified Files:
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pgsql-server/src/test/regress:
pg_regress.sh (r1.44 -> r1.45)
(http://developer.postgresql.org/cvsweb.cgi/pgsql-server/src/test/regress/pg_regress.sh.diff?r1=1.44&r2=1.45)