lwip: Fix compatibility issues with later versions

The name of the header guard in lwIP's <lwip/opt.h> has changed from
'__LWIP_OPT_H__' to 'LWIP_HDR_OPT_H' (bug #35874 in May 2015).

Other fixes:

- In curl_setup.h, the problem with an old PSDK doesn't apply if lwIP is
used.

- In memdebug.h, the 'socket' should be undefined first due to lwIP's
lwip_socket() macro.

- In curl_addrinfo.c lwIP's getaddrinfo() + freeaddrinfo() macros need
special handling because they were undef'ed in memdebug.h.

- In select.c we can't use preprocessor conditionals inside select if
MSVC and select is a macro, as it is with lwIP.

http://curl.haxx.se/mail/lib-2015-12/0023.html
http://curl.haxx.se/mail/lib-2015-12/0024.html

include/curl/curl.h

@@ -56,7 +56,8 @@
 #include <time.h>
 
 #if defined(WIN32) && !defined(_WIN32_WCE) && !defined(__CYGWIN__)
-#if !(defined(_WINSOCKAPI_) || defined(_WINSOCK_H) || defined(__LWIP_OPT_H__))
+#if !(defined(_WINSOCKAPI_) || defined(_WINSOCK_H) || \
+      defined(__LWIP_OPT_H__) || defined(LWIP_HDR_OPT_H))
 /* The check above prevents the winsock2 inclusion if winsock.h already was
    included, since they can't co-exist without problems */
 #include <winsock2.h>
@@ -112,7 +113,7 @@ typedef void CURL;
 
 #ifndef curl_socket_typedef
 /* socket typedef */
-#if defined(WIN32) && !defined(__LWIP_OPT_H__)
+#if defined(WIN32) && !defined(__LWIP_OPT_H__) && !defined(LWIP_HDR_OPT_H)
 typedef SOCKET curl_socket_t;
 #define CURL_SOCKET_BAD INVALID_SOCKET
 #else