Update libexecinfo man page for FreeBSD

Sponsored by:	DARPA, AFRL

contrib/libexecinfo/backtrace.3

@@ -1,4 +1,5 @@
 .\"	$NetBSD: backtrace.3,v 1.4 2012/06/10 00:24:36 christos Exp $
+.\"	$FreeBSD$
 .\"
 .\" Copyright (c) 2012 The NetBSD Foundation, Inc.
 .\" All rights reserved.
@@ -27,7 +28,7 @@
 .\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 .\" POSSIBILITY OF SUCH DAMAGE.
 .\"
-.Dd May 26, 2012
+.Dd August 23, 2013
 .Dt BACKTRACE 3
 .Os
 .Sh NAME
@@ -116,7 +117,7 @@ on failure.
 .Sh RETURN VALUES
 The
 .Fn backtrace
-function returns the number of elements tht were filled in the backtrace.
+function returns the number of elements that were filled in the backtrace.
 The
 .Fn backtrace_symbols
 and
@@ -133,7 +134,9 @@ Diagnostic output may also be produced by the ELF symbol lookup functions.
 The
 .Fn backtrace
 library of functions first appeared in
-.Nx 7.0 .
+.Nx 7.0
+and
+.Fx 10.0 .
 .Sh BUGS
 .Bl -enum
 .It
@@ -150,10 +153,9 @@ instead of
 .Ft size_t
 arguments.
 .It
-Since
-.Xr dladdr 3
-only deals with dynamic symbols, we need to find the symbols from the main
-portion of the program.
-For that we need to locate the executable, and we use procfs for
-finding it, which is not portable.
+The
+.Fn backtrace_symbols
+functions currently rely on
+.Xr procfs 5
+to locate the executable.
 .El