Windows: Cleanup of src/config/NTMakefile

Windows: Cleanup of src/config/NTMakefile

src/config/NTMakefile had the following issues:

 * duplicate entries for headers in $(INCFILES)

 * no clean: rule for $(INCFILES)

 * no clean: rule for $(DESTDIR)\util_cr.exe

 * $(INCTOOLS) dependent upon $(INCFILES) but the order is reversed
   in the install: rule

Change-Id: I2707009d60b303ab897ed25d9245d893fa342a8e
Reviewed-on: http://gerrit.openafs.org/2238
Reviewed-by: Jeffrey Altman <jaltman@openafs.org>
Tested-by: Jeffrey Altman <jaltman@openafs.org>
Reviewed-by: Matt Benjamin <matt@linuxbox.com>
Tested-by: Matt Benjamin <matt@linuxbox.com>