libgui/SF: Fix some code warnings

A couple of fixes to satisfy the Eclipse static code analysis tool.
- Initialize all members in constructors
- Remove unused forward declarations
- Add parentheses when combining logical and bitwise operators
- Fix a case statement with no break (it was intentional)

Change-Id: Icecb8cc98c6f58b97ab33fffb621f0edc33a7d3c
diff --git a/libs/gui/SurfaceComposerClient.cpp b/libs/gui/SurfaceComposerClient.cpp
index 6ad47d8..9167a0c 100644
--- a/libs/gui/SurfaceComposerClient.cpp
+++ b/libs/gui/SurfaceComposerClient.cpp
@@ -310,9 +310,9 @@
     layer_state_t* s = getLayerStateLocked(client, id);
     if (!s)
         return BAD_INDEX;
-    if (mask & layer_state_t::eLayerOpaque ||
-            mask & layer_state_t::eLayerHidden ||
-            mask & layer_state_t::eLayerSecure) {
+    if ((mask & layer_state_t::eLayerOpaque) ||
+            (mask & layer_state_t::eLayerHidden) ||
+            (mask & layer_state_t::eLayerSecure)) {
         s->what |= layer_state_t::eFlagsChanged;
     }
     s->flags &= ~mask;