Fix memory corruption when trying to get "core show locks".

Review https://reviewboard.asterisk.org/r/2580/ tried to fix the mismatch
in memory pools but had a math error determining the buffer size and
didn't address other similar memory pool mismatches.

* Effectively reverted the previous patch to go in the same direction as
trunk for the returned memory pool of ast_bt_get_symbols().

* Fixed memory leak in ast_bt_get_symbols() when BETTER_BACKTRACES is
defined.

* Fixed some formatting in ast_bt_get_symbols().

* Fixed sig_pri.c freeing memory allocated by libpri when MALLOC_DEBUG is
enabled.

* Fixed __dump_backtrace() freeing memory from ast_bt_get_symbols() when
MALLOC_DEBUG is enabled.

* Moved __dump_backtrace() because of compile issues with the utils
directory.

(closes issue ASTERISK-22221)
Reported by: Matt Jordan

Review: https://reviewboard.asterisk.org/r/2778/
........

Merged revisions 397525 from http://svn.asterisk.org/svn/asterisk/branches/1.8


git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/11@397528 65c4cc65-6c06-0410-ace0-fbb531ad65f3

main/lock.c

@@ -29,6 +29,7 @@
 
 ASTERISK_FILE_VERSION(__FILE__, "$Revision$")
 
+#include "asterisk/utils.h"
 #include "asterisk/lock.h"
 
 /* Allow direct use of pthread_mutex_* / pthread_cond_* */
@@ -45,6 +46,22 @@ ASTERISK_FILE_VERSION(__FILE__, "$Revision$")
 #undef pthread_cond_wait
 #undef pthread_cond_timedwait
 
+#if defined(DEBUG_THREADS) && defined(HAVE_BKTR)
+static void __dump_backtrace(struct ast_bt *bt, int canlog)
+{
+	char **strings;
+	ssize_t i;
+
+	strings = backtrace_symbols(bt->addresses, bt->num_frames);
+
+	for (i = 0; i < bt->num_frames; i++) {
+		__ast_mutex_logger("%s\n", strings[i]);
+	}
+
+	ast_std_free(strings);
+}
+#endif	/* defined(DEBUG_THREADS) && defined(HAVE_BKTR) */
+
 int __ast_pthread_mutex_init(int tracking, const char *filename, int lineno, const char *func,
 						const char *mutex_name, ast_mutex_t *t)
 {