Add classlib and segments tool

This is the first step to track different segments of the classfile
backend in our benchmarks.

Change-Id: Ie16b8a3db76da54d54b2efc373a25cb9d10cb99b
diff --git a/third_party/classlib.tar.gz.sha1 b/third_party/classlib.tar.gz.sha1
new file mode 100644
index 0000000..c0ecd4f
--- /dev/null
+++ b/third_party/classlib.tar.gz.sha1
@@ -0,0 +1 @@
+b5beda30c42f557ae55af0df14b363782a6fee60
\ No newline at end of file