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/services/surfaceflinger/tests/LayerTransactionTest.h b/services/surfaceflinger/tests/LayerTransactionTest.h
index b87c734..6758518 100644
--- a/services/surfaceflinger/tests/LayerTransactionTest.h
+++ b/services/surfaceflinger/tests/LayerTransactionTest.h
@@ -19,6 +19,7 @@
 // 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 <gtest/gtest.h>
 #include <gui/ISurfaceComposer.h>
@@ -306,4 +307,4 @@
 } // namespace android
 
 // TODO(b/129481165): remove the #pragma below and fix conversion issues
-#pragma clang diagnostic pop // ignored "-Wconversion"
\ No newline at end of file
+#pragma clang diagnostic pop // ignored "-Wconversion -Wextra"
\ No newline at end of file