scripts: in case of failed download, remove partial files

It happens from time to time that the server mis-behaves, and breaks the
connection right in the middle of nowhere, for no good reason, leaving us
with a partial file, on which the extract pass would choke.

Remove partial downloads, to fail early.

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@anciens.enib.fr>
(transplanted from eefacabd9e72f3d578e5dc5908026ed780f9a240)

--- binutils/libiberty/Makefile.in.mps	2004-05-13 15:53:17.000000000 +0200

+++ binutils/libiberty/Makefile.in	2004-05-13 15:52:53.000000000 +0200

@@ -224,6 +224,7 @@ $(TARGETLIB): $(REQUIRED_OFILES) $(EXTRA

 	  $(AR) $(AR_FLAGS) $(TARGETLIB) \

 	    $(REQUIRED_OFILES) $(EXTRA_OFILES) $(LIBOBJS); \

 	  $(RANLIB) $(TARGETLIB); \

+	  cp $(TARGETLIB) ../ ; \

 	  cd ..; \

 	else true; fi