VS: connect /Y- compiler option with "Not Using Precompiled Headers"

The change allows to selectively disable PrecompiledHeaders.
Despite the `$(VCTargetsPath)/1033/cl.xml` contains an empty value for switch,
for effectively turn off setting need to use /Y- option as described on msdn:
https://msdn.microsoft.com/en-us/library/1hy7a92h.aspx
20 jobs for connect_disablePCH_with_cl_option
Status Job ID Name Coverage
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passed cmake-dash3win7-windows-release-ninja

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