break out on first error

mk/build.mk

@@ -572,6 +572,7 @@ release:
 			$(GMAKE) VERBOSE=1 all; if [ $$? -ne 0 ]; then touch .exit; exit 1;fi; \
 			rm .config; \
 		) 2>&1 | tee $(TOPDIR)/bin/$(SYSTEM)_$(ARCH)_$$libc/build.log; \
+		if [ -f .exit ];then break;fi \
 	done
 
 # build all target architecture, target systems and libc combinations