Remove unneeded sigproc.h includes throughout.

* fhandler.h (fhandler_proc::fill_filebuf): Take a pinfo argument.
* fhandler_proc.cc (fhandler_proc::get_proc_fhandler): Simplify search for
given pid.
(fhandler_proc::readdir): Assume that pid exists if it shows up in the winpid
list.
* fhandler_process.cc (fhandler_process::open): Simplify search for given pid.
Call fill_filebuf with pinfo argument.
(fhandler_process::fill_filebuf): Pass pinfo here and assume that it exists.
* pinfo.h (pinfo::remember): Define differently if sigproc.h is not included.
* dll_init.cc (dll_list::detach): Don't run destructor on exit.

winsup/cygwin/pinfo.h

@@ -8,6 +8,8 @@ This software is a copyrighted work licensed under the terms of the
 Cygwin license.  Please consult the file "CYGWIN_LICENSE" for
 details. */
 
+#ifndef _PINFO_H
+#define _PINFO_H
 /* Signal constants (have to define them here, unfortunately) */
 
 enum
@@ -152,7 +154,11 @@ public:
   _pinfo *operator * () const {return procinfo;}
   operator _pinfo * () const {return procinfo;}
   // operator bool () const {return (int) h;}
+#ifdef _SIGPROC_H
   int remember () {destroy = 0; return proc_subproc (PROC_ADDCHILD, (DWORD) this);}
+#else
+  int remember () {system_printf ("remember is not here"); return 0;}
+#endif
   HANDLE shared_handle () {return h;}
 };
 
@@ -206,3 +212,4 @@ int __stdcall fixup_shms_after_fork ();
 
 void __stdcall fill_rusage (struct rusage *, HANDLE);
 void __stdcall add_rusage (struct rusage *, struct rusage *);
+#endif /*_PINFO_H*/