While the flag tables for C and C++ were generated from MSBuild `.xml`
files, the CSharp flag tables were written by hand. Copy the `v143`
flag table to use for the `v145` toolset.
While the flag tables for C and C++ were generated from MSBuild `.xml`
files, the CSharp flag tables were written by hand. Copy the `v142`
flag table to use for the `v143` toolset.