HalManifests can be merged.

assemble_vintf and VintfObject can now merge manifests
correctly (previously, only <hal>'s are merged).

Test: libvintf_test
Test: vintf_object_test
Fixes: 78943004
Change-Id: I5e2987e9c97e0b60e976fe4e0bb8833edf043a53
diff --git a/SystemSdk.cpp b/SystemSdk.cpp
index d2ee123..1dfd463 100644
--- a/SystemSdk.cpp
+++ b/SystemSdk.cpp
@@ -32,5 +32,10 @@
     return versions() == other.versions();
 }
 
+void SystemSdk::addAll(SystemSdk* other) {
+    mVersions.insert(other->mVersions.begin(), other->mVersions.end());
+    other->mVersions.clear();
+}
+
 }  // namespace vintf
 }  // namespace android