pgsql: Honor MSVC WindowsSDKVersion if set

Honor MSVC WindowsSDKVersion if set

Add a line to the project file setting the target SDK. Otherwise, in for
example VS2017, if the default but optional 8.1 SDK is not installed the
build will fail.

Patch from Peifeng Qiu, slightly edited by me.

Discussion: /messages/by-id/CABmtVJhw1boP_bd4=b3Qv5YnqEdL696NtHFi2ruiyQ6mFHkeQQ@mail.gmail.com

Backpatch to all live branches.

Branch
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REL_12_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/6e5417d7737bdcc26ca7889210f275a8e46591b0

Modified Files
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src/tools/msvc/MSBuildProject.pm | 13 +++++++++++++
1 file changed, 13 insertions(+)