[Rd] incomplete make clean for grDevices ( Windows only) (PR#8137)

[thomas.petzoldt@tu-dresden.de]

Full_Name: Thomas Petzoldt
Version: R 2.2.0 alpha
OS: Windows
Submission from: (NULL) (141.30.20.2)


Symptom:

If one moves a source tree to another drive letter, a following compile will
fail when compiling grDevices.

The bug is found on Windows only.

Reason:

When performing a "make clean" for the complete installation, several files (in
particular *.d are not cleaned up.

Suggested solution: 

modify Makefile.win that "clean" deletes *.rd (and possibly some others??)

clean:
	$(RM) $(DLLNAME).dll *.a $(OBJS) $(DLLNAME).def grDevices_res.rc *.d