pgsql: Add define to exclude configured libraries, to be able to easily

Log Message:
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Add define to exclude configured libraries, to be able to easily build a
stripped down version of libpq. To be used by the installer.

Modified Files:
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pgsql/src/tools/msvc:
Solution.pm (r1.17 -> r1.18)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/tools/msvc/Solution.pm.diff?r1=1.17&r2=1.18)