Обсуждение: pgsql: Make the msvc build system ask python about details of version

Log Message:
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Make the msvc build system ask python about details of version and installation
prefix, instead of assuming it will always be following the default layout.

All information we need is not available on Windows, but the number of
assumptions are at least fewer this way than before.

Based on suggestions from James William Pye.

Modified Files:
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    pgsql/src/tools/msvc:
        Mkvcbuild.pm (r1.51 -> r1.52)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/tools/msvc/Mkvcbuild.pm?r1=1.51&r2=1.52)