Codebase Gardening. NFC.

1. Eliminate unused variable warnings.
2. Change field names to match capitalization of the rest of the field names in the file.
3. Change method names to match rest of the file.
4. Change get,set method for a field to match the field type.

Swift SVN r24501

lib/SIL/SILModule.cpp

@@ -740,7 +740,7 @@ void SILModule::eraseFunction(SILFunction *F) {
     // or vtable stub generation. So we move it into the zombie list.
     getFunctionList().remove(F);
     zombieFunctions.push_back(F);
-    F->markAsZombie();
+    F->setZombie();
 
     // This opens dead-function-removal opportunities for called functions.
     // (References are not needed anymore.)