Hidlized version of IMemory.

- Add hidl_memory type.
- Add android.hidl.memory@1.0 package
  - IMapper
  - IAllocator
  - IMemory
- Add libhidlmemory
- Add default implementation of android.hidl.memory@1.0
  - Ashmem
  - Ion (TODO, probably in another CL)

Test: compiles (WIP)
Change-Id: I4632eeb6a0051551b54ce04d919aaf551dfc5f28
diff --git a/Android.bp b/Android.bp
index ea670fa..5fe6ad5 100644
--- a/Android.bp
+++ b/Android.bp
@@ -13,8 +13,9 @@
 // limitations under the License.
 
 subdirs = [
-    "base",         // libhidlbase
-    "transport",    // libhidl
+    "base",           // libhidlbase
+    "libhidlmemory",  // libhidlmemory
+    "transport",      // libhidltransport
 ]
 
 cc_test {