* 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/syscalls.cc

@@ -24,6 +24,8 @@ details. */
 #include <unistd.h>
 #include <winnls.h>
 #include <lmcons.h> /* for UNLEN */
+#include "dtable.h"
+#include "pinfo.h"
 
 extern BOOL allow_ntsec;