Fix a missing config.h dependency when building sparseset.o to prevent
"conflicting types for 'strsignal'" error, which can intermittently crop
up for high values of make -j.

Thanks to Richard Purdie and Jeff Dike for their help in tracking this
down.

Scott Garman <scott.a.garman@intel.com> 2010-07-13
diff -urN gcc-4.3.3.orig//gcc/Makefile.in gcc-4.3.3/gcc/Makefile.in
--- gcc-4.3.3.orig//gcc/Makefile.in	2008-12-04 15:00:19.000000000 -0800
+++ gcc-4.3.3/gcc/Makefile.in	2010-07-13 21:30:01.864681358 -0700
@@ -1789,7 +1789,7 @@
     $(FLAGS_H) hard-reg-set.h $(BASIC_BLOCK_H) $(OBSTACK_H)
 ebitmap.o: ebitmap.c $(CONFIG_H) $(SYSTEM_H) coretypes.h $(TM_H) \
 	$(EBITMAP_H)
-sparseset.o: sparseset.c $(SYSTEM_H) sparseset.h
+sparseset.o: sparseset.c $(CONFIG_H) $(SYSTEM_H) sparseset.h
 
 COLLECT2_OBJS = collect2.o tlink.o intl.o version.o
 COLLECT2_LIBS = @COLLECT2_LIBS@