libssh2_socket_t: now externally visible

In preparation for upcominig changes, the libssh2_socket_t type is now
typedef'ed in the public header.

include/libssh2.h

@@ -130,6 +130,13 @@ typedef unsigned long long libssh2_uint64_t;
 typedef long long libssh2_int64_t;
 #endif
 
+#ifdef WIN32
+typedef SOCKET libssh2_socket_t;
+#else /* !WIN32 */
+typedef int libssh2_socket_t;
+#define INVALID_SOCKET -1
+#endif /* WIN32 */
+
 /* Part of every banner, user specified or not */
 #define LIBSSH2_SSH_BANNER                  "SSH-2.0-libssh2_" LIBSSH2_VERSION
 

src/libssh2_priv.h

@@ -145,13 +145,6 @@ static inline int writev(int sock, struct iovec *iov, int nvecs)
 
 #endif
 
-#ifdef WIN32
-typedef SOCKET libssh2_socket_t;
-#else /* !WIN32 */
-typedef int libssh2_socket_t;
-#define INVALID_SOCKET -1
-#endif /* WIN32 */
-
 /* RFC4253 section 6.1 Maximum Packet Length says:
  *
  * "All implementations MUST be able to process packets with