* winsup.h: Split out dtable definitions into separate header file.

* dtable.h: New file.
* sigproc.h: Eliminate pinfo.h usage here.  Use it in source files that need
it.

winsup/cygwin/net.cc

@@ -23,6 +23,8 @@ details. */
 #include <fcntl.h>
 #include "autoload.h"
 #include <winsock.h>
+#include "dtable.h"
+#include "pinfo.h"
 
 /* We only want to initialize WinSock in a child process if socket
    handles are inheritted. This global allows us to know whether this