Sync guest SubAllocator with host version

+ make it a different class to avoid odr violation

Change-Id: I81079ee5aee9e5066acd9f797c49c094dc5df196
diff --git a/BUILD.gn b/BUILD.gn
index c6e0201..b02c012 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -5,8 +5,8 @@
     "android-emu/android/base/Pool.cpp",
     "android-emu/android/base/Pool.h",
     "android-emu/android/base/ring_buffer.c",
-    "android-emu/android/base/SubAllocator.cpp",
-    "android-emu/android/base/SubAllocator.h",
+    "android-emu/android/base/AndroidSubAllocator.cpp",
+    "android-emu/android/base/AndroidSubAllocator.h",
     "android-emu/android/base/files/MemStream.cpp",
     "android-emu/android/base/files/MemStream.h",
     "android-emu/android/base/files/Stream.cpp",