Revert much of previous erroneous checkin. Add ChangeLog entry.

* pinfo.h: Correctly set __SIGOFFSET.
* path.cc (hash_path_name): Avoid calling library functions for simple copying
of characters.
* shortcut.c: Use WIN32_LEAN_AND_MEAN.
* smallprint.c: Ditto.
* environ.cc (getwinenv): Minor clarity fix.
* localtime.c: No need to include windows.h
* string.h: New file.

winsup/cygwin/winsup.h

@@ -14,8 +14,6 @@ details. */
 
 #define __INSIDE_CYGWIN__
 
-#include "interlock.h"
-
 #define alloca __builtin_alloca
 #define strlen __builtin_strlen
 #define strcmp __builtin_strcmp
@@ -35,7 +33,6 @@ details. */
 #include <sys/types.h>
 #include <sys/strace.h>
 
-
 extern char case_folded_lower[];
 #define cyg_tolower(c) (case_folded_lower[(unsigned char)(c)])
 extern char case_folded_upper[];