jimtcl: update embedded jimtcl

Update to latest jimtcl commit 2c1eba991e21a6f0b531fb0f83e21f9e6ee7c515.
This fixes issues when building on certain versions of Mac OSX.

Change-Id: I551477752d7913c84e6deb60b889d0c14bd200a0
Signed-off-by: Spencer Oliver <spen@spen-soft.co.uk>
Reviewed-on: http://openocd.zylin.com/1311
Tested-by: jenkins
Reviewed-by: Xiaofan <xiaofanc@gmail.com>

diff --git a/jimtcl b/jimtcl
index 43d0866133a899532fb459a35860060add504923..2c1eba991e21a6f0b531fb0f83e21f9e6ee7c515 160000 (submodule)
--- a/jimtcl
+++ b/jimtcl
@@ -1 +1 @@
-Subproject commit 43d0866133a899532fb459a35860060add504923
+Subproject commit 2c1eba991e21a6f0b531fb0f83e21f9e6ee7c515