SF: Compile with -Wextra

Compile with -Wextra for additional conversion checks. In each file
which produces compile errors -Wextra is ignored.

Bug: 175126758
Test: m surfaceflinger && m libsurfaceflinger_unittest
Change-Id: Iec6bcc699715a99c8c65d891ab3c0481e884c728
diff --git a/libs/renderengine/tests/RenderEngineTest.cpp b/libs/renderengine/tests/RenderEngineTest.cpp
index d9dfd8c..47b8cad 100644
--- a/libs/renderengine/tests/RenderEngineTest.cpp
+++ b/libs/renderengine/tests/RenderEngineTest.cpp
@@ -20,6 +20,7 @@
 // TODO(b/129481165): remove the #pragma below and fix conversion issues
 #pragma clang diagnostic push
 #pragma clang diagnostic ignored "-Wconversion"
+#pragma clang diagnostic ignored "-Wextra"
 
 #include <chrono>
 #include <condition_variable>
@@ -1844,4 +1845,4 @@
 } // namespace android
 
 // TODO(b/129481165): remove the #pragma below and fix conversion issues
-#pragma clang diagnostic pop // ignored "-Wconversion"
+#pragma clang diagnostic pop // ignored "-Wconversion -Wextra"