Add support for win32.

Edit win32/config.mk to set the paths to your openssl and zlib headers and
libraries.

Then, from the root of the tree:

	nmake -f NMakefile

voila.

win32/libssh2_config.h

@@ -0,0 +1,31 @@
+#define WIN32
+#include <winsock2.h>
+#include <mswsock.h>
+#include <ws2tcpip.h>
+
+/* same as WSABUF */
+struct iovec {
+	u_long iov_len;
+	char *iov_base;
+};
+
+#define inline __inline
+
+static inline int writev(int sock, struct iovec *iov, int nvecs)
+{
+	DWORD ret;
+	if (WSASend(sock, (LPWSABUF)iov, nvecs, &ret, 0, NULL, NULL) == 0) {
+		return ret;
+	}
+	return -1;
+}
+
+/* not really usleep, but safe for the way we use it in this lib */
+static inline int usleep(int udelay)
+{
+	Sleep(udelay / 1000);
+	return 0;
+}
+
+#define snprintf	_snprintf
+