Specifies the target argument for vcvarsall.bat (Visual C++ command that sets the path and environment variables for command-line builds according to the target architecture). This option is only used if compiling on a Windows platform. The default is "x86" for architecture = "32" and "x64" for architecture = "64", i.e., native 32-bit or 64-bit compilation is assumed. All other cross-compilation options, such as "x86_amd64" (x86 cross-compiler for x64 targets) or "amd64_x86" (x64 cross-compiler for x86 targets), must be explicitly specified via this option. Please consult your MSVC documentation as required target options vary with Microsoft Visual Studio versions.