If we receive ZT_EVENT_REMOVED, destroy the specified channel.

(issue #7256, tzafrir)

Also, update the configure script to make sure that we don't try to build 
chan_zap if the installed version of zaptel does not include ZT_EVENT_REMOVED.


git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/1.4@58320 65c4cc65-6c06-0410-ace0-fbb531ad65f3

configure.ac

@@ -1026,7 +1026,7 @@ if test "${USE_ZAPTEL}" != "no"; then
 fi
 
 if test "${PBX_ZAPTEL}" = 1; then
-   AC_MSG_CHECKING(for ZT_TONE_DTMF_BASE in zaptel/zaptel.h)
+   AC_MSG_CHECKING(for ZT_EVENT_REMOVED in zaptel/zaptel.h)
    saved_cppflags="${CPPFLAGS}"
    if test "x${ZAPTEL_DIR}" != "x"; then
       CPPFLAGS="${CPPFLAGS} -I${ZAPTEL_DIR}/include"
@@ -1035,7 +1035,7 @@ if test "${PBX_ZAPTEL}" = 1; then
 	[
 	AC_LANG_PROGRAM(
 	[#include <zaptel/zaptel.h>],
-	[int foo = ZT_TONE_DTMF_BASE;])
+	[int foo = ZT_EVENT_REMOVED;])
 	],
 	[	AC_MSG_RESULT(yes) 
 		ac_cv_zaptel_vldtmf="yes"