Merge pull request swiftlang#39565 from apple/compnerd/5.5-2990e8bc070aee69b3a1cdecfd526ebf0f7ec5fa

build: repair the build with VS2019 16.10.0

Author: shahmishal

cmake/modules/Libdispatch.cmake

@@ -92,6 +92,7 @@ foreach(sdk ${DISPATCH_SDKS})
                           -DCMAKE_INSTALL_LIBDIR=lib
                           -DCMAKE_INSTALL_PREFIX=<INSTALL_DIR>
                           -DCMAKE_LINKER=${CMAKE_LINKER}
+                          -DCMAKE_MT=${CMAKE_MT}
                           -DCMAKE_RANLIB=${CMAKE_RANLIB}
                           -DCMAKE_TOOLCHAIN_FILE=${CMAKE_TOOLCHAIN_FILE}
                           -DCMAKE_SYSTEM_NAME=${SWIFT_SDK_${sdk}_NAME}