As discussed in https://forums.adobe.com/message/9123283 and https://github.com/litehelpers/Cordova-sqlite-legacy-build-support/issues/10 it is not possible to build on PhoneGap Build for Windows with a plugin such as https://github.com/litehelpers/Cordova-sqlite-legacy-build-support or https://github.com/litehelpers/Cordova-sqlite-evcore-extbuild-free. The solution discussed in https://github.com/litehelpers/Cordova-sqlite-legacy-build-support/issues/10 is to build the Windows C++ library by hand then include the WinMD file in plugin.xml just like https://github.com/phonegap/phonegap-plugin-barcodescanner/blob/master/plugin.xml#L65-L67.
But as discussed in https://github.com/litehelpers/Cordova-sqlite-legacy-build-support/issues/10 this is still not possible since we need to include both WinMD and DLL files in case of a C++ library.
I hereby raise this issue to fix cordova-windows to support WinMD+DLL for C++ libraries such as https://github.com/litehelpers/Cordova-sqlite-legacy-build-support. This is a blocking issue for one of my customers.