Move dex CFG dumping out of utils.cc

Move CFG dumping to dexdump, the only client.

Bug: 22322814
Test: test-art-host
Change-Id: I0f39f1d5dfc446419d26d709b78d04e45616f42c
diff --git a/dexdump/Android.bp b/dexdump/Android.bp
index 3e589f7..60ce363 100644
--- a/dexdump/Android.bp
+++ b/dexdump/Android.bp
@@ -18,6 +18,7 @@
     name: "dexdump2",
     host_supported: true,
     srcs: [
+        "dexdump_cfg.cc",
         "dexdump_main.cc",
         "dexdump.cc",
     ],