Add README.android to compiler-rt project.

Change-Id: I466cc3d89cb800ddcb216c0eb5e1f16aefcf736f
diff --git a/README.android b/README.android
new file mode 100644
index 0000000..d4bd6a4
--- /dev/null
+++ b/README.android
@@ -0,0 +1,23 @@
+/*
+ * README.android describes in high-level the compiler-rt changes that we
+ * cannot push upstream to the llvm.org repository:
+ *  - Changes due to Android's build system.
+ *  - Changes due to Android's toolchain.
+ *  - Changes due to the limitations in Android-based consumer electronics.
+ *
+ * Some of them are to-dos. If and when they are done, there will no longer be
+ * merge conflicts with upstream on those parts.
+ *
+ * The file contains useful hints when we try to resolve future 3-way merge
+ * conflicts.
+ */
+
+* For JellyBean: Synced to upstream r152058
+
+* Recent downstreaming on 2012/03/08: Synced to r152058 (Contact srhines for merge questions.)
+
+TODO: This is still not building by default (no Android.mk files are present
+yet). Look at frameworks/compile/libbcc/runtime for potential starting points.
+
+TODO: Switch libbcc to use this version of compiler-rt instead of its own
+tweaked version.