windows: set CMAKE_MSVC_RUNTIME_LIBRARY for zlib

Since v1.3, zlib advertises compatibility with CMake 3.15 which prefers
to leave the MSVC runtime library selection flags out of the default
CMAKE_<LANG>_FLAGS_<CONFIG> values and instead offer a first-class
abstraction.

The CMAKE_MSVC_RUNTIME_LIBRARY variable and MSVC_RUNTIME_LIBRARY target
property may be set to select the MSVC runtime library. If they are not
set then CMake uses the default value

    MultiThreaded$<$<CONFIG:Debug>:Debug>DLL

which is equivalent to the flags for dynamic linking. This causes
linking errors when building the statically linked Win32 version of
libfido2. Adjust the default depending on our target build type to also
allow for static linking.

[1] https://cmake.org/cmake/help/latest/prop_tgt/MSVC_RUNTIME_LIBRARY.html

windows/build.ps1

@@ -183,6 +183,7 @@ try {
 	    -DBUILD_SHARED_LIBS="${SHARED}" `
 	    -DCMAKE_C_FLAGS_DEBUG="${CFLAGS_DEBUG}" `
 	    -DCMAKE_C_FLAGS_RELEASE="${CFLAGS_RELEASE}" `
+	    -DCMAKE_MSVC_RUNTIME_LIBRARY="${CMAKE_MSVC_RUNTIME_LIBRARY}" `
 	    -DCMAKE_INSTALL_PREFIX="${PREFIX}" "${CMAKE_SYSTEM_VERSION}"; `
 	    ExitOnError
 	& $CMake --build . --config ${Config} --verbose; ExitOnError

windows/const.ps1

@@ -34,9 +34,13 @@ New-Variable -Name 'PREFIX' -Value "${OUTPUT}\${Arch}\${Type}" -Option Constant
 if ("${Type}" -eq "dynamic") {
 	New-Variable -Name 'RUNTIME' -Value '/MD' -Option Constant
 	New-Variable -Name 'SHARED' -Value 'ON' -Option Constant
+	New-Variable -Name 'CMAKE_MSVC_RUNTIME_LIBRARY' -Option Constant `
+	    -Value 'MultiThreaded$<$<CONFIG:Debug>:Debug>DLL'
 } else {
 	New-Variable -Name 'RUNTIME' -Value '/MT' -Option Constant
 	New-Variable -Name 'SHARED' -Value 'OFF' -Option Constant
+	New-Variable -Name 'CMAKE_MSVC_RUNTIME_LIBRARY' -Option Constant `
+	    -Value 'MultiThreaded$<$<CONFIG:Debug>:Debug>'
 }
 New-Variable -Name 'CFLAGS_DEBUG' -Value "${RUNTIME}d /Zi /guard:cf /sdl" `
     -Option Constant