Makefile: use make -C

make provides a handy -C option to change directory before reading
the makefiles or doing anything else.

Use that instead of the "cd dir && make && cd .." pattern, thus
simplifying sintax for some makefiles.

Changes from v1:
- Drop an obviously wrong leftover on testsuite/iproute2/Makefile

Signed-off-by: Andrea Claudi <aclaudi@redhat.com>
Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>

Makefile

@@ -114,7 +114,8 @@ clobber:
 distclean: clobber
 
 check: all
-	cd testsuite && $(MAKE) && $(MAKE) alltests
+	$(MAKE) -C testsuite
+	$(MAKE) -C testsuite alltests
 	@if command -v man >/dev/null 2>&1; then \
 		echo "Checking manpages for syntax errors..."; \
 		$(MAKE) -C man check; \

testsuite/Makefile

@@ -26,10 +26,10 @@ endif
 .PHONY: compile listtests alltests configure $(TESTS)
 
 configure:
-	echo "Entering iproute2" && cd iproute2 && $(MAKE) configure && cd ..;
+	$(MAKE) -C iproute2 configure
 
 compile: configure generate_nlmsg
-	echo "Entering iproute2" && cd iproute2 && $(MAKE) && cd ..;
+	$(MAKE) -C iproute2
 
 listtests:
 	@for t in $(TESTS); do \
@@ -51,7 +51,7 @@ clean: testclean
 	$(MAKE) -C tools clean
 
 distclean: clean
-	echo "Entering iproute2" && cd iproute2 && $(MAKE) distclean && cd ..;
+	$(MAKE) -C iproute2 distclean
 
 $(TESTS): generate_nlmsg testclean
 ifeq (,$(IPVERS))

testsuite/iproute2/Makefile

@@ -4,7 +4,7 @@ SUBDIRS := $(filter-out Makefile,$(wildcard *))
 
 all: configure
 	@for dir in $(SUBDIRS); do \
-		echo "Entering $$dir" && cd $$dir && $(MAKE) && cd ..; \
+		$(MAKE) -C $$dir; \
 	done
 
 link:
@@ -19,12 +19,12 @@ configure: link
 
 clean: link
 	@for dir in $(SUBDIRS); do \
-		echo "Entering $$dir" && cd $$dir && $(MAKE) clean && cd ..; \
+		$(MAKE) -C $$dir clean; \
 	done
 
 distclean: clean
 	@for dir in $(SUBDIRS); do \
-		echo "Entering $$dir" && cd $$dir && $(MAKE) distclean && cd ..; \
+		$(MAKE) -C $$dir distclean; \
 	done
 
 show: link