res/Makefile: alias dist-clean to distclean

A 'make distclean' is equivalent to 'make dist-clean' in the top most Makefile.
This patch updates the res/Makefile to recognize both distclean and dist-clean.
Note that this is needed for removing build.mak, which can run into problems
if the source file of Asterisk or its path is changed after build.mak is
generated.

(issue ASTERISK-22480)
Reported by: Matt Jordan


git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/11@405362 65c4cc65-6c06-0410-ace0-fbb531ad65f3

res/Makefile

@@ -70,7 +70,8 @@ clean::
 	@if [ -f pjproject/build.mak ]; then $(MAKE) -C pjproject realclean; fi
 	rm -f snmp/*.o snmp/*.i ael/*.o ael/*.i ais/*.o ais/*.i
 
-dist-clean::
+dist-clean:: distclean
+distclean::
 	rm -f pjproject/build.mak
 
 pjproject/build.mak: pjproject/aconfigure
@@ -92,4 +93,5 @@ res_rtp_asterisk.o: _ASTCFLAGS+=-DUSE_PJPROJECT
 res_rtp_asterisk.o: _ASTCFLAGS+=$(PJ_CFLAGS)
 res_rtp_asterisk.so: _ASTLDFLAGS+=$(PJ_LDFLAGS)
 res_rtp_asterisk.so: LIBS+=$(PJ_LDLIBS)
-endif
+endif
+