scp client and server ported to work in Windows

Lot of code had to be redone as scp.exe contains both the scp client and
scp server in the same binary working in Windows needs various file
system access related changes. sshd_config file needs to add "scp"
subsystem path like we do for sftp server.

Author: quamrulmina

contrib/win32/win32compat/socket.c

@@ -1676,8 +1676,8 @@ int peekPipeRead(int sfd)
 
     if (!ret)
     {
-      error("PeekNamedPipe on sfd [%d] failed with error code [%d]",
-                sfd, GetLastError());
+      //error("PeekNamedPipe on sfd [%d] failed with error code [%d]",
+      //          sfd, GetLastError());
       return 0;
     }