Import broadcast_ring.h from GVR (reland)

This will be used as a transport by the pose plumbing.

Remove host_supported=true from the blueprint. Although this library is
portable C++11, some of the tests aren't, and I don't know how to test
the various SDK targets in order to properly #ifdef them.

Bug: 37102512
Test: m -j32 broadcast_ring_tests; broadcast_ring_tests

Change-Id: Ib91387f2feba9030d2e892dc5145e353b88bad45
diff --git a/libs/vr/libbroadcastring/Android.bp b/libs/vr/libbroadcastring/Android.bp
new file mode 100644
index 0000000..13af470
--- /dev/null
+++ b/libs/vr/libbroadcastring/Android.bp
@@ -0,0 +1,35 @@
+cc_library_static {
+    name: "libbroadcastring",
+    clang: true,
+    cflags: [
+        "-Wall",
+        "-Wextra",
+        "-Werror",
+    ],
+    export_include_dirs: ["include"],
+    shared_libs: [
+        "libbase",
+    ],
+    export_shared_lib_headers: [
+        "libbase",
+    ],
+}
+
+cc_test {
+    name: "broadcast_ring_tests",
+    clang: true,
+    cflags: [
+        "-Wall",
+        "-Wextra",
+        "-Werror",
+    ],
+    srcs: [
+        "broadcast_ring_test.cc",
+    ],
+    static_libs: [
+        "libbroadcastring",
+    ],
+    shared_libs: [
+        "libbase",
+    ],
+}