Fix compilation when NO_CURL is defined

There were a few places which did not cope well without curl.  This
fixes all of them.  We still need to link against the walker.o part
of the library as some parts of transport.o still call into there
even though we don't have HTTP support enabled.

If compiled with NO_CURL=1 we now get the following useful error
message:

  $ git-fetch http://www.example.com/git
  error: git was compiled without libcurl support.
  fatal: Don't know how to fetch from http://www.example.com/git

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>

Makefile

@@ -310,7 +310,7 @@ LIB_OBJS = \
 	alloc.o merge-file.o path-list.o help.o unpack-trees.o $(DIFF_OBJS) \
 	color.o wt-status.o archive-zip.o archive-tar.o shallow.o utf8.o \
 	convert.o attr.o decorate.o progress.o mailmap.o symlinks.o remote.o \
-	transport.o bundle.o
+	transport.o bundle.o walker.o
 
 BUILTIN_OBJS = \
 	builtin-add.o \
@@ -528,7 +528,7 @@ else
 	endif
 	BUILTIN_OBJS += builtin-http-fetch.o
 	EXTLIBS += $(CURL_LIBCURL)
-	LIB_OBJS += http.o walker.o http-walker.o
+	LIB_OBJS += http.o http-walker.o
 	curl_check := $(shell (echo 070908; curl-config --vernum) | sort -r | sed -ne 2p)
 	ifeq "$(curl_check)" "070908"
 		ifndef NO_EXPAT
@@ -905,7 +905,7 @@ git-http-push$X: revision.o http.o http-push.o $(GITLIBS)
 	$(QUIET_LINK)$(CC) $(ALL_CFLAGS) -o $@ $(ALL_LDFLAGS) $(filter %.o,$^) \
 		$(LIBS) $(CURL_LIBCURL) $(EXPAT_LIBEXPAT)
 
-$(LIB_OBJS) $(BUILTIN_OBJS) walker.o: $(LIB_H)
+$(LIB_OBJS) $(BUILTIN_OBJS): $(LIB_H)
 $(patsubst git-%$X,%.o,$(PROGRAMS)): $(LIB_H) $(wildcard */*.h)
 $(DIFF_OBJS): diffcore.h
 

transport.c

@@ -1,7 +1,9 @@
 #include "cache.h"
 #include "transport.h"
 #include "run-command.h"
+#ifndef NO_CURL
 #include "http.h"
+#endif
 #include "pkt-line.h"
 #include "fetch-pack.h"
 #include "walker.h"
@@ -368,6 +370,7 @@ static int disconnect_walker(struct transport *transport)
 	return 0;
 }
 
+#ifndef NO_CURL
 static int curl_transport_push(struct transport *transport, int refspec_nr, const char **refspec, int flags) {
 	const char **argv;
 	int argc;
@@ -400,7 +403,6 @@ static int curl_transport_push(struct transport *transport, int refspec_nr, cons
 	return !!err;
 }
 
-#ifndef NO_CURL
 static int missing__target(int code, int result)
 {
 	return	/* file:// URL -- do we ever use one??? */
@@ -504,21 +506,6 @@ static int fetch_objs_via_curl(struct transport *transport,
 	return fetch_objs_via_walker(transport, nr_objs, to_fetch);
 }
 
-#else
-
-static struct ref *get_refs_via_curl(const struct transport *transport)
-{
-	die("Cannot fetch from '%s' without curl ...", transport->url);
-	return NULL;
-}
-
-static int fetch_objs_via_curl(struct transport *transport,
-				 int nr_objs, struct ref **to_fetch)
-{
-	die("Cannot fetch from '%s' without curl ...", transport->url);
-	return -1;
-}
-
 #endif
 
 struct bundle_transport_data {
@@ -733,9 +720,13 @@ struct transport *transport_get(struct remote *remote, const char *url)
 	} else if (!prefixcmp(url, "http://")
 	        || !prefixcmp(url, "https://")
 	        || !prefixcmp(url, "ftp://")) {
+#ifdef NO_CURL
+		error("git was compiled without libcurl support.");
+#else
 		ret->get_refs_list = get_refs_via_curl;
 		ret->fetch = fetch_objs_via_curl;
 		ret->push = curl_transport_push;
+#endif
 		ret->disconnect = disconnect_walker;
 
 	} else if (is_local(url) && is_file(url)) {