make: add 'checksrc' as target to check code style

The make target checksrc now works in the root makefile and in both the
src and lib directories.

It is also run automatically on "all" if configure --enable-debug was
used.

Makefile.am

@@ -155,3 +155,7 @@ ca-bundle: lib/mk-ca-bundle.pl
 ca-firefox: lib/firefox-db2pem.sh
 	@echo "generate a fresh ca-bundle.crt"
 	./lib/firefox-db2pem.sh lib/ca-bundle.crt
+
+checksrc:
+	cd lib && $(MAKE) checksrc
+	cd src && $(MAKE) checksrc

lib/Makefile.am

@@ -185,9 +185,11 @@ $(VCPROJ): vc8proj.head vc8proj.foot Makefile.am
 	done; \
 	cat $(srcdir)/vc8proj.foot $(VCPROJOUT) )
 
+
+checksrc:
+	@@PERL@ $(top_srcdir)/lib/checksrc.pl -D$(top_srcdir)/lib $(CSOURCES) $(HHEADERS)
+
 if CURLDEBUG
 # for debug builds, we scan the sources on all regular make invokes
-all-local:
-	@@PERL@ $(top_srcdir)/lib/checksrc.pl -D$(top_srcdir)/lib $(CSOURCES) $(HHEADERS)
+all-local: checksrc
 endif
-

src/Makefile.am

@@ -96,10 +96,12 @@ $(HUGE):
 	echo "void hugehelp(void) {}" >>$(HUGE)
 endif
 
-if CURLDEBUG
-# for debug builds, we scan the sources on all regular make invokes
 # ignore hugehelp.c since it is generated source code and it plays by slightly
 # different rules!
-all-local:
+checksrc:
 	@@PERL@ $(top_srcdir)/lib/checksrc.pl -D$(top_srcdir)/src -Whugehelp.c $(curl_SOURCES)
+
+if CURLDEBUG
+# for debug builds, we scan the sources on all regular make invokes
+all-local: checksrc
 endif