fakehwc, libvr_hwc-hal: ComposerClient is moved

ComposerClient is moved to another library with some changes.  This
allows us to kill the has-a relation between VrComposerClient and
ComposerClientImpl in VR.

Test: builds
Change-Id: I0c32386f7d62f33e2e4d1271be42953f6880fd75
diff --git a/services/surfaceflinger/tests/fakehwc/FakeComposerService.cpp b/services/surfaceflinger/tests/fakehwc/FakeComposerService.cpp
index c411604..f70cbdb 100644
--- a/services/surfaceflinger/tests/fakehwc/FakeComposerService.cpp
+++ b/services/surfaceflinger/tests/fakehwc/FakeComposerService.cpp
@@ -46,7 +46,9 @@
 
 Return<void> FakeComposerService::createClient(createClient_cb hidl_cb) {
     ALOGI("FakeComposerService::createClient %p", mClient.get());
-    mClient->initialize();
+    if (!mClient->init()) {
+        LOG_ALWAYS_FATAL("failed to initialize ComposerClient");
+    }
     hidl_cb(Error::NONE, mClient);
     return Void();
 }