Fixed extconf.c breakage introduced in r376306.

To quote wdoekes:
> Note that I'm not confirming legitimacy of having that file in tree at
> all. Is anyone using aelparse/conf2ael?
........

Merged revisions 376340 from http://svn.asterisk.org/svn/asterisk/branches/1.8
........

Merged revisions 376342 from http://svn.asterisk.org/svn/asterisk/branches/10


git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/11@376343 65c4cc65-6c06-0410-ace0-fbb531ad65f3

utils/extconf.c

@@ -153,6 +153,7 @@ void ast_console_puts(const char *string);
 #define LOG_DTMF    __LOG_DTMF, _A_
 
 /* lock.h */
+#define _ASTERISK_LOCK_H /* A small indication that this is horribly wrong. */
 
 #ifndef	HAVE_MTX_PROFILE
 #define	__MTX_PROF(a)	return pthread_mutex_lock((a))