Fixes #557: Now `WINDOWS_EXPORT_ALL_SYMBOLS` just for our targets; an… #542

Job	Run time
build (windows-2019, 12.1.1, Visual Studio 16 2019, powershell, windows, -A x64)	12m 59s
build (windows-2019, 12.0.1, Visual Studio 16 2019, powershell, windows, -A x64)	12m 14s
build (windows-2019, 11.8.0, Visual Studio 16 2019, powershell, windows, -A x64)	12m 9s
build (windows-2019, 11.7.0, Visual Studio 16 2019, powershell, windows, -A x64)	6m 42s
build (windows-2019, 11.6.2, Visual Studio 16 2019, powershell, windows, -A x64)	13m 5s
build (windows-2019, 11.6.1, Visual Studio 16 2019, powershell, windows, -A x64)	8m 36s
build (windows-2019, 11.6.0, Visual Studio 16 2019, powershell, windows, -A x64)	5m 15s
build (windows-2019, 11.5.0, Visual Studio 16 2019, powershell, windows, -A x64)	4m 51s
build (windows-2019, 11.4.0, Visual Studio 16 2019, powershell, windows, -A x64)	7m 52s
build (windows-2019, 11.3.0, Visual Studio 16 2019, powershell, windows, -A x64)	7m 58s
build (windows-2019, 11.2.2, Visual Studio 16 2019, powershell, windows, -A x64)	6m 3s
build (windows-2019, 11.1.1, Visual Studio 16 2019, powershell, windows, -A x64)	7m 44s
build (windows-2019, 11.0.3, Visual Studio 16 2019, powershell, windows, -A x64)	9m 16s
	1h 54m 44s

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