cygwin: make <sys/socket.h> completely visible from <netinet/in.h>

While POSIX mandates that certain socket types shall be defined by the
inclusing of <netinet/in.h>, it also says that this header may also make
visible all <sys/socket.h> symbols.  Glibc does this, and without out it,
some packages end up requiring an additional #include <sys/socket.h>.

Signed-off-by: Yaakov Selkowitz <yselkowi@redhat.com>

winsup/cygwin/include/cygwin/in.h

@@ -18,7 +18,7 @@
 #ifndef _CYGWIN_IN_H
 #define _CYGWIN_IN_H
 
-#include <cygwin/socket.h>
+#include <sys/socket.h>
 
 #ifndef _IN_ADDR_T_DECLARED
 typedef	__uint32_t	in_addr_t;