Bump libgit2.

Rob Rix · Rob Rix · commit 99ccb2f28214 · 2015-03-06T11:07:05.000-05:00
diff --git a/External/libgit2 b/External/libgit2
@@ -1 +1 @@
-Subproject commit d5712ed2b33a18a4f9417d112bda7813c0570caa
+Subproject commit bdf0e734506b5b18234d48a0e7c6995aeda30b9d
