Sign Windows binaries on Linux host

[gudvinr]

Currently, when you cross-compile application for different platform, code sign will fail for GOOS=windows on Linux and Mac because of missing signtool.exe.

Same will happen if you try to compile for GOOS=darwin on Linux and Windows.

However, there is osslsigncode for creating Authenticode signatures, which uses openssl and can be used to sign PE binaries on non-windows hosts.

windowsCodesign then can either check presence of osslsigncode if signtool.exe does not exist or use runtime.GOOS to switch code paths.