[binutils-gdb] Add missing PR reference in ChangeLog

[Simon Marchi]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=fec93fb13d2cc088ba3e1aa944f3c2c02616edf1

commit fec93fb13d2cc088ba3e1aa944f3c2c02616edf1
Author: Simon Marchi <simon.marchi@ericsson.com>
Date:   Fri Jan 20 20:47:41 2017 -0500

    Add missing PR reference in ChangeLog

Diff:
---
 gdb/ChangeLog | 1 +
 1 file changed, 1 insertion(+)

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index d3268f3..6311d91 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,5 +1,6 @@
 2017-01-20  Simon Marchi  <simon.marchi@ericsson.com>
 
+	PR python/21068
 	* python/python-internal.h (PyMem_RawMalloc): Define for
 	Python < 3.4.
 	* python/py-gdb-readline.c (gdbpy_readline_wrapper): Use