If the import of "C" is immediately preceded by a comment, that
comment, called the preamble, is used as a header when compiling
the C parts of the package. For example:

	// #include <stdio.h>
	// #include <errno.h>
	import "C"

The preamble may contain any C code, including function and variable
declarations and definitions. These may then be referred to from Go
code as though they were defined in the package "C". All names

pkg syscall (windows-386), const WSAENOPROTOOPT = 10042 #62254
pkg syscall (windows-386), const WSAENOPROTOOPT Errno #62254
pkg syscall (windows-amd64), const WSAENOPROTOOPT = 10042 #62254