Allow parallel make (-j) to work properly.

After some back and forth with the reporter, we came up with the necessary changes.

(closes issue #16489)
Reported by: Chainsaw
Patches:
      asterisk-1.6.2.1-parallel-make-minimal.patch uploaded by Chainsaw (license 723)
Tested by: Chainsaw, qwell


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@241230 65c4cc65-6c06-0410-ace0-fbb531ad65f3

Makefile

@@ -598,7 +598,7 @@ bininstall: _all installdirs $(SUBDIRS_INSTALL)
 	fi
 
 $(SUBDIRS_INSTALL):
-	@DESTDIR="$(DESTDIR)" ASTSBINDIR="$(ASTSBINDIR)" $(SUBMAKE) -C $(@:-install=) install
+	+@DESTDIR="$(DESTDIR)" ASTSBINDIR="$(ASTSBINDIR)" $(SUBMAKE) -C $(@:-install=) install
 
 NEWMODS:=$(foreach d,$(MOD_SUBDIRS),$(notdir $(wildcard $(d)/*.so)))
 OLDMODS=$(filter-out $(NEWMODS),$(notdir $(wildcard $(DESTDIR)$(MODULES_DIR)/*.so)))
@@ -867,7 +867,7 @@ cleantest:
 	@cmp -s .cleancount .lastclean || $(MAKE) clean
 
 $(SUBDIRS_UNINSTALL):
-	@$(SUBMAKE) -C $(@:-uninstall=) uninstall
+	+@$(SUBMAKE) -C $(@:-uninstall=) uninstall
 
 _uninstall: $(SUBDIRS_UNINSTALL)
 	rm -f $(DESTDIR)$(MODULES_DIR)/*