Avoid leaking current data on generated file for Ada.

Index: gcc/ada/gcc-interface/Makefile.in
===================================================================
--- gcc/ada/gcc-interface/Makefile.in	(revision 268977)
+++ gcc/ada/gcc-interface/Makefile.in	(working copy)
@@ -2407,6 +2407,7 @@ $(RTSDIR)/s-oscons.ads: ../stamp-gnatlib
 	    $(OSCONS_CPP) ; \
 	    $(OSCONS_EXTRACT) ; \
 	    ../bldtools/oscons/xoscons s-oscons)
+	touch -r $(fsrcpfx)ada/gsocket.h $@
 
 gnatlib: ../stamp-gnatlib1-$(RTSDIR) ../stamp-gnatlib2-$(RTSDIR) $(RTSDIR)/s-oscons.ads
 	test -f $(RTSDIR)/s-oscons.ads || exit 1