Add README.version for external/compiler-rt.

(cherry picked from commit 04fd89c64361a4570e6b081ea12ce37ba766c463)

Change-Id: I76fe6b3781d6740738541f3a9e84f19639ea0556
diff --git a/README.version b/README.version
new file mode 100644
index 0000000..c9d92df
--- /dev/null
+++ b/README.version
@@ -0,0 +1,4 @@
+URL: http://llvm.org/git/compiler-rt.git
+Version: Rolling from upstream + cherry-picks
+BugComponent: 117395
+Owners: srhines, android-llvm