build: fix some inconsistencies in install commands

Changes:

* Remove / after `$(DESTDIR)`
* Remove useless -c
* Use 0755 instead of 755
* Use -d after -m

See also commit dae3933 ("rework make realinstall and uninstall
(netblue30#3435)", 2020-06-04).

Makefile

@@ -245,8 +245,8 @@ endif
 	$(INSTALL) -m 0755 -d $(DESTDIR)$(sysconfdir)/firejail/firecfg.d
 	$(INSTALL) -m 0644 -t $(DESTDIR)$(sysconfdir)/firejail src/firecfg/firecfg.config
 	$(INSTALL) -m 0644 -t $(DESTDIR)$(sysconfdir)/firejail etc/profile-a-l/*.profile etc/profile-m-z/*.profile etc/inc/*.inc etc/net/*.net etc/firejail.config
-	sh -c "if [ ! -f $(DESTDIR)/$(sysconfdir)/firejail/login.users ]; then \
-		$(INSTALL) -c -m 0644 etc/login.users $(DESTDIR)/$(sysconfdir)/firejail/.; \
+	sh -c "if [ ! -f $(DESTDIR)$(sysconfdir)/firejail/login.users ]; then \
+		$(INSTALL) -m 0644 etc/login.users $(DESTDIR)$(sysconfdir)/firejail/.; \
 	fi"
 ifeq ($(HAVE_IDS),-DHAVE_IDS)
 	$(INSTALL) -m 0644 -t $(DESTDIR)$(sysconfdir)/firejail etc/ids.config
@@ -256,21 +256,20 @@ ifeq ($(BUSYBOX_WORKAROUND),yes)
 endif
 ifeq ($(HAVE_APPARMOR),-DHAVE_APPARMOR)
 	# install apparmor profile
-	sh -c "if [ ! -d $(DESTDIR)/$(sysconfdir)/apparmor.d ]; then \
-		$(INSTALL) -d -m 755 $(DESTDIR)/$(sysconfdir)/apparmor.d; \
+	sh -c "if [ ! -d $(DESTDIR)$(sysconfdir)/apparmor.d ]; then \
+		$(INSTALL) -m 0755 -d $(DESTDIR)$(sysconfdir)/apparmor.d; \
 	fi"
 	$(INSTALL) -m 0644 etc/apparmor/firejail-default $(DESTDIR)$(sysconfdir)/apparmor.d
 	# install apparmor profile customization file
-	sh -c "if [ ! -d $(DESTDIR)/$(sysconfdir)/apparmor.d/local ]; then \
-		$(INSTALL) -d -m 755 $(DESTDIR)/$(sysconfdir)/apparmor.d/local; \
+	sh -c "if [ ! -d $(DESTDIR)$(sysconfdir)/apparmor.d/local ]; then \
+		$(INSTALL) -m 0755 -d $(DESTDIR)$(sysconfdir)/apparmor.d/local; \
 	fi"
-	sh -c "if [ ! -f $(DESTDIR)/$(sysconfdir)/apparmor.d/local/firejail-default ]; then \
-		$(INSTALL) -c -m 0644 etc/apparmor/firejail-local \
-		  $(DESTDIR)/$(sysconfdir)/apparmor.d/local/firejail-default; \
+	sh -c "if [ ! -f $(DESTDIR)$(sysconfdir)/apparmor.d/local/firejail-default ]; then \
+		$(INSTALL) -m 0644 etc/apparmor/firejail-local $(DESTDIR)$(sysconfdir)/apparmor.d/local/firejail-default; \
 	fi"
 	# install apparmor base abstraction drop-in
-	sh -c "if [ ! -d $(DESTDIR)/$(sysconfdir)/apparmor.d/abstractions/base.d ]; then \
-		$(INSTALL) -d -m 755 $(DESTDIR)/$(sysconfdir)/apparmor.d/abstractions/base.d; \
+	sh -c "if [ ! -d $(DESTDIR)$(sysconfdir)/apparmor.d/abstractions/base.d ]; then \
+		$(INSTALL) -m 0755 -d $(DESTDIR)$(sysconfdir)/apparmor.d/abstractions/base.d; \
 	fi"
 	$(INSTALL) -m 0644 etc/apparmor/firejail-base $(DESTDIR)$(sysconfdir)/apparmor.d/abstractions/base.d
 endif