[bug] "make install" with unprivileged user fails with nonexisting "/bin/true".

- Some platforms (at releast macOS) has only "/usr/bin/true".

Makefile.am

@@ -94,9 +94,9 @@ authorcheck:
 
 install-data-hook: installdir installconfig nextstep importantchanges
 if SMTPC
-	-chown $(USER) $(DESTDIR)$(libexecdir)/sympa_smtpc
-	-chgrp $(GROUP) $(DESTDIR)$(libexecdir)/sympa_smtpc
-	-chmod 750 $(DESTDIR)$(libexecdir)/sympa_smtpc
+	-@chown $(USER) $(DESTDIR)$(libexecdir)/sympa_smtpc
+	-@chgrp $(GROUP) $(DESTDIR)$(libexecdir)/sympa_smtpc
+	-@chmod 750 $(DESTDIR)$(libexecdir)/sympa_smtpc
 endif
 
 installdir:
@@ -108,7 +108,7 @@ installdir:
 		fi; \
 	done
 	@echo "Creating writable directories"
-	@for dir in $(expldir) $(spooldir) $(spooldir)/msg $(spooldir)/digest \
+	-@for dir in $(expldir) $(spooldir) $(spooldir)/msg $(spooldir)/digest \
 		$(spooldir)/moderation $(spooldir)/auth \
 		$(spooldir)/outgoing $(spooldir)/tmp $(spooldir)/task \
 		$(spooldir)/bulk \
@@ -117,8 +117,8 @@ installdir:
 			echo "Creating $(DESTDIR)$$dir"; \
 			$(INSTALL) -d -m 755 $(DESTDIR)$$dir; \
 		fi; \
-		chown $(USER) $(DESTDIR)$$dir || /bin/true; \
-		chgrp $(GROUP) $(DESTDIR)$$dir || /bin/true; \
+		chown $(USER) $(DESTDIR)$$dir; \
+		chgrp $(GROUP) $(DESTDIR)$$dir; \
 	done
 
 sympa_wizard.pl.inst: $(top_srcdir)/src/sbin/sympa_wizard.pl.in Makefile
@@ -129,38 +129,37 @@ sympa_wizard.pl.inst: $(top_srcdir)/src/sbin/sympa_wizard.pl.in Makefile
 
 installconfig: installdir sympa_wizard.pl.inst
 	@echo "Installing basic configuration ..."
-	export PERL5LIB=$(DESTDIR)$(modulesdir); \
+	-@export PERL5LIB=$(DESTDIR)$(modulesdir); \
 	if [ ! -f  $(DESTDIR)$(confdir)/sympa.conf ]; then \
 		echo "This looks like your first Sympa installation. The following wizard will assist you to create your first Sympa configuration.";\
 		if [ ! -d $(DESTDIR)$(confdir) ]; then \
 			$(INSTALL) -d -m 755 $(DESTDIR)$(confdir); \
 		fi; \
-		chown $(USER) $(DESTDIR)$(confdir) || /bin/true; \
-		chgrp $(GROUP) $(DESTDIR)$(confdir) || /bin/true; \
+		chown $(USER) $(DESTDIR)$(confdir); \
+		chgrp $(GROUP) $(DESTDIR)$(confdir); \
 		$(PERL) sympa_wizard.pl.inst \
 			--create sympa.conf \
-			--target $(DESTDIR)$(confdir)/sympa.conf \
-			|| /bin/true; \
-		chown $(USER) $(DESTDIR)$(confdir)/sympa.conf || /bin/true; \
-		chgrp $(GROUP) $(DESTDIR)$(confdir)/sympa.conf || /bin/true; \
-	fi; \
-	if [ ! -f $(DESTDIR)$(sysconfdir)/data_structure.version ]; then \
+			--target $(DESTDIR)$(confdir)/sympa.conf; \
+		chown $(USER) $(DESTDIR)$(confdir)/sympa.conf; \
+		chgrp $(GROUP) $(DESTDIR)$(confdir)/sympa.conf; \
+	fi
+	-@if [ ! -f $(DESTDIR)$(sysconfdir)/data_structure.version ]; then \
 		cd $(DESTDIR)$(sysconfdir); \
 		echo "# automatically created file" >> data_structure.version; \
 		echo "# you should not modify it" >> data_structure.version; \
 		echo $(VERSION) >> data_structure.version; \
-		chown $(USER) data_structure.version || /bin/true; \
-		chgrp $(GROUP) data_structure.version || /bin/true; \
+		chown $(USER) data_structure.version; \
+		chgrp $(GROUP) data_structure.version; \
 	fi
-	@for dir in create_list_templates custom_actions custom_conditions \
+	-@for dir in create_list_templates custom_actions custom_conditions \
 		data_sources families global_task_models list_task_models \
 		mail_tt2 scenari search_filters web_tt2; do \
 		if [ ! -d $(DESTDIR)$(sysconfdir)/$$dir ] ; then \
 			echo "Creating $(DESTDIR)$(sysconfdir)/$$dir"; \
 			$(INSTALL) -d -m 755 $(DESTDIR)$(sysconfdir)/$$dir; \
 		fi; \
-		chown $(USER) $(DESTDIR)$(sysconfdir)/$$dir || /bin/true; \
-		chgrp $(GROUP) $(DESTDIR)$(sysconfdir)/$$dir || /bin/true; \
+		chown $(USER) $(DESTDIR)$(sysconfdir)/$$dir; \
+		chgrp $(GROUP) $(DESTDIR)$(sysconfdir)/$$dir; \
 	done
 	@if [ ! -e $(DESTDIR)$(sysconfdir)/README ]; then \
 		echo "Creating $(DESTDIR)$(sysconfdir)/README"; \
@@ -192,7 +191,7 @@ nextstep:
 	@echo "#######################################################"
 
 importantchanges:
-	if test -f $(top_srcdir)/previous_sympa_version; then \
+	@if test -f $(top_srcdir)/previous_sympa_version; then \
 		export PREVIOUS=`$(CAT) $(top_srcdir)/previous_sympa_version`; \
 	fi; \
 	$(PERL) $(top_srcdir)/important_changes.pl \