Fix memory leak in res_calendar_ews when event email address node is empty

If the XML calendar data returned by a Microsoft Exchange Web Service
specifies an XML Event E-Mail Address ("EmailAddress"), and no e-mail address
is provided, a condition existed where an ast_calendar_attendee struct would
be allocated but not appended to the list of attendees.  Because of that,
the memory associated with the attendee would never be freed.  This patch
frees the memory if no e-mail address is provided.
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Merged revisions 361606 from http://svn.asterisk.org/svn/asterisk/branches/1.8
........

Merged revisions 361607 from http://svn.asterisk.org/svn/asterisk/branches/10


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@361608 65c4cc65-6c06-0410-ace0-fbb531ad65f3

res/res_calendar_ews.c

@@ -424,6 +424,8 @@ static int endelm(void *userdata, int state, const char *nspace, const char *nam
 		if (ast_str_strlen(ctx->cdata)) {
 			attendee->data = ast_strdup(ast_str_buffer(ctx->cdata));
 			AST_LIST_INSERT_TAIL(&ctx->event->attendees, attendee, next);
+		} else {
+			ast_free(attendee);
 		}
 		ast_debug(3, "EWS: XML: attendee address '%s'\n", ast_str_buffer(ctx->cdata));
 		ast_str_reset(ctx->cdata);