Fix missing $ for escaping shell variables for make

Makefile.am

@@ -45,7 +45,7 @@ DEFAULT_SOUNDS=en-us-callie-8000
 	 sounds_version=`grep $$base_sound_dir $(switch_srcdir)/build/sounds_version.txt | cut -d ' '  -f2`;\
 	 soundfile=`echo freeswitch-sounds-$$full_sound_dir-$$moh_version.tar.gz`; \
 	 echo $$full_sound_dir | grep  music  >/dev/null || soundfile=`echo freeswitch-sounds-$$full_sound_dir-$$sounds_version.tar.gz`; \
-	 args="$@"; if test -z "$$args" || test "$${args#-l*}" = "$args"; then \
+	 args="$@"; if test -z "$$args" || test "$${args#-l*}" = "$$args"; then \
 	   if test "$$target_prefix" = "sounds"; then \
 	     if test "$$target" = "install"; then \
 	        $(GETSOUNDS) $$soundfile $(DESTDIR)$(soundsdir)/;\