Shared/Build: Restore disabled warnings on Visual Studio

Restore 2 disabled warnings, 1 already disabled in CMake with the WITH_WARNINGS flag set to False and the other disabled by default as stated in VS documentation http://msdn.microsoft.com/en-us/library/aa984150.aspx
Merge pull request #10827 from jackpoz/restore_warnings

Shared/Build: Restore disabled warnings on Visual Studio