Link shell with compat layer functions

This in the short term will break on platforms that use compat implemenations
that call outside compat layer, but that is exactly what we want.  To give
incentive to fix things for people who are affected and more importantly have
environment to test their fixes.
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

Makefile

@@ -324,6 +324,7 @@ endif
 export PERL_PATH
 
 LIB_FILE=libgit.a
+COMPAT_LIB = compat/lib.a
 XDIFF_LIB=xdiff/lib.a
 
 LIB_H += archive.h
@@ -1203,8 +1204,11 @@ 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)
 
-git-shell$X: compat/strlcpy.o abspath.o ctype.o exec_cmd.o quote.o strbuf.o usage.o wrapper.o shell.o
-	$(QUIET_LINK)$(CC) $(ALL_CFLAGS) -o $@ $(ALL_LDFLAGS) $(filter %.o,$^)
+$(COMPAT_LIB): $(COMPAT_OBJS)
+	$(QUIET_AR)$(RM) $@ && $(AR) rcs $@ $(COMPAT_OBJS)
+
+git-shell$X: abspath.o ctype.o exec_cmd.o quote.o strbuf.o usage.o wrapper.o shell.o $(COMPAT_LIB)
+	$(QUIET_LINK)$(CC) $(ALL_CFLAGS) -o $@ $(ALL_LDFLAGS) $(filter %.o,$^) $(COMPAT_LIB)
 
 $(LIB_OBJS) $(BUILTIN_OBJS): $(LIB_H)
 $(patsubst git-%$X,%.o,$(PROGRAMS)): $(LIB_H) $(wildcard */*.h)
@@ -1402,7 +1406,7 @@ distclean: clean
 
 clean:
 	$(RM) *.o mozilla-sha1/*.o arm/*.o ppc/*.o compat/*.o xdiff/*.o \
-		$(LIB_FILE) $(XDIFF_LIB)
+		$(LIB_FILE) $(XDIFF_LIB) $(COMPAT_LIB)
 	$(RM) $(ALL_PROGRAMS) $(BUILT_INS) git$X
 	$(RM) $(TEST_PROGRAMS)
 	$(RM) *.spec *.pyc *.pyo */*.pyc */*.pyo common-cmds.h TAGS tags cscope*