Trouble interfacing with C/C++ single-header library

[marcomq]

I used following build options and was able to compile the webview.cc file in 
nim 
<https://github.com/marcomq/nimview/blob/e45d7a63f1d83ab11cb5f5e3b2ce62fee19e3c3a/src/nimview/webview2/src/webview/header.nim#L13>