FallThroughScope: remove SwitchBreak type

A `SwitchBreak` node should not have a specific associated
`FallThroughScopeType`, since its semantics represent the fact of a
`case` of the `switch` with no associated statements, and thus can be
represented with the `FallThrough` behavior.

lib/RestructureCFG/FallThroughScopeAnalysis.cpp

@@ -227,7 +227,10 @@ fallThroughScopeImpl(const model::Binary &Model,
     rc_return FallThroughScopeType::FallThrough;
   } break;
   case ASTNode::NK_SwitchBreak: {
-    rc_return FallThroughScopeType::SwitchBreak;
+
+    // `The `SwitchBreak` represents the fact that we fallthrough from the
+    // switch out
+    rc_return FallThroughScopeType::FallThrough;
   } break;
   case ASTNode::NK_Continue: {
     rc_return FallThroughScopeType::Continue;

lib/RestructureCFG/FallThroughScopeAnalysis.h

@@ -21,7 +21,6 @@ enum class FallThroughScopeType {
   Return,
   Continue,
   LoopBreak,
-  SwitchBreak,
 };
 
 using FallThroughScopeTypeMap = std::map<const ASTNode *, FallThroughScopeType>;

lib/RestructureCFG/PromoteCallNoReturn.cpp

@@ -30,8 +30,7 @@ static bool isPreferredAsFallThrough(FallThroughScopeType Element) {
   switch (Element) {
   case FallThroughScopeType::Return:
   case FallThroughScopeType::Continue:
-  case FallThroughScopeType::LoopBreak:
-  case FallThroughScopeType::SwitchBreak: {
+  case FallThroughScopeType::LoopBreak: {
     return true;
   } break;
   case FallThroughScopeType::FallThrough: