don't clean target

mk/build.mk

@@ -623,7 +623,6 @@ bulkallmod:
 		$(GMAKE) prereq && \
 		$(GMAKE) ARCH=$$arch SYSTEM=$$system LIBC=$$libc FS=archive allmodconfig; \
 		$(GMAKE) VERBOSE=1 all; if [ $$? -ne 0 ]; then echo $$system-$$libc >.exit; exit 1;fi; \
-		$(GMAKE) cleantarget; \
 		rm .config; \
             ) 2>&1 | tee $(TOPDIR)/bin/$${system}_$${arch}_$$libc/build.log; \
 	      done; \