[pango] Add note re threadsafe libthai

[Behdad Esfahbod <behdad src gnome org>]

commit 39c8cfcc614f8901d347a047b3295a06082cbfee
Author: Behdad Esfahbod <behdad behdad org>
Date:   Thu Oct 22 14:20:47 2015 -0200

    Add note re threadsafe libthai

 pango/break-thai.c |    5 +++++
 1 files changed, 5 insertions(+), 0 deletions(-)
---
diff --git a/pango/break-thai.c b/pango/break-thai.c
index 659e96e..5560c9f 100644
--- a/pango/break-thai.c
+++ b/pango/break-thai.c
@@ -27,6 +27,11 @@
 #include <thai/thwchar.h>
 #include <thai/thbrk.h>
 
+/* TODO
+ * LibThai 0.1.23 claims to be thread-safe.
+ * Check that and avoid locking?
+ * http://linux.thai.net/node/286
+ */
 G_LOCK_DEFINE_STATIC (th_brk);
 
 /*