Windows CE port fixes/enhancements (from <Someone>)

A few other fixes:
- bug: text window does not scroll left on left arrow
- pcmain.c: fix warning: _fileno() returns void* in Windows CE SDK

3.5.0 only:
- files.c: compile error: don't include <signal.h> if NO_SIGNAL is defined. WinMo does not support POSIX signals
- version.c: compile error: append_port_id() is undeclared
- link error: mktime() is unsupported -> define it in celib.c

-<Someone>

include/extern.h

@@ -2400,6 +2400,10 @@ E unsigned long FDECL(get_feature_notice_ver, (char *));
 E unsigned long NDECL(get_current_feature_ver);
 E const char *FDECL(copyright_banner_line, (int));
 
+#ifdef RUNTIME_PORT_ID
+E void FDECL(append_port_id, (char *));
+#endif
+
 /* ### video.c ### */
 
 #ifdef MSDOS