MinGW: fix compile error due to missing ELOOP

MinGW and MSVC before 2010 don't define ELOOP, use EMLINK (aka "Too many
links") instead.

Signed-off-by: Karsten Blees <blees@dcon.de>
Reviewed-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

compat/mingw.h

@@ -35,6 +35,9 @@ typedef int socklen_t;
 #ifndef EWOULDBLOCK
 #define EWOULDBLOCK EAGAIN
 #endif
+#ifndef ELOOP
+#define ELOOP EMLINK
+#endif
 #define SHUT_WR SD_SEND
 
 #define SIGHUP 1