proposed fix for Bug 3598300
merge trunk
remove some EXTERN and CONST usages in tclWinPort.h
More flexible search for win32 tclConfig.sh, backported from TEA (not actually used in Tcl, only for Tk)
[Bug 3598300]: unix: tcl.h does not include sys/stat.h
[Bug 3598300]: unix: tcl.h does not include sys/stat.h
[Bug 3598300]: unix: tcl.h does not include sys/stat.h