Add more constness to the end_buf pointer in the netconsole

issue ASTERISK-18308
Review: https://reviewboard.asterisk.org/r/1876/
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Merged revisions 364046 from http://svn.asterisk.org/svn/asterisk/branches/1.8
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Merged revisions 364047 from http://svn.asterisk.org/svn/asterisk/branches/10


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@364048 65c4cc65-6c06-0410-ace0-fbb531ad65f3

main/asterisk.c

@@ -1272,7 +1272,7 @@ static void *netconsole(void *vconsole)
 	char hostname[MAXHOSTNAMELEN] = "";
 	char inbuf[512];
 	char outbuf[512];
-	const char *end_buf = inbuf + sizeof(inbuf);
+	const char * const end_buf = inbuf + sizeof(inbuf);
 	char *start_read = inbuf;
 	int res;
 	struct pollfd fds[2];