[lldb] Silence GCC warnings about control reaching the end of non-void functions. NFC.

[mstorsjo]

Summary

Also remove a superfluous semicolon after the braces for a switch
statement (that wasn't warned about).

[dblaikie]

I'm guessing this change will break the build in a different way, triggering clang's -Wcovered-switch-default - the usual way this gcc/clang diagnostic pinch is resolved is by putting the unreachable after the switch/at the end of the function, instead of in a default case.

[mstorsjo]

Moved unreachable to outside of switch

[dblaikie]

Looks good - thanks! Do you need me to commit this for you?

[mstorsjo]

In D100447#2688172, @dblaikie wrote:

Looks good - thanks! Do you need me to commit this for you?

Thanks, but I've got commit access!

lldb/source/Plugins/LanguageRuntime/ObjC/AppleObjCRuntime/AppleObjCRuntimeV2.cpp

AppleObjCRuntimeV2::DynamicClassInfoExtractor::GetClassInfoUtilityFunction(
   case objc_copyRealizedClassList: {
     if (!m_objc_copyRealizedClassList_helper.utility_function)
       m_objc_copyRealizedClassList_helper.utility_function =
           GetClassInfoUtilityFunctionImpl(exe_ctx,
                                           g_get_dynamic_class_info2_body,
                                           g_get_dynamic_class_info2_name);
     return m_objc_copyRealizedClassList_helper.utility_function.get();
   }
-  };
+  }
+  llvm_unreachable("Unexpected helper");
 }
 
 lldb::addr_t &
 AppleObjCRuntimeV2::DynamicClassInfoExtractor::GetClassInfoArgs(Helper helper) {
   switch (helper) {
   case gdb_objc_realized_classes:
     return m_gdb_objc_realized_classes_helper.args;
   case objc_copyRealizedClassList:
     return m_objc_copyRealizedClassList_helper.args;
   }
+  llvm_unreachable("Unexpected helper");
 }
 
 AppleObjCRuntimeV2::DynamicClassInfoExtractor::Helper
 AppleObjCRuntimeV2::DynamicClassInfoExtractor::ComputeHelper() const {
   if (!m_runtime.m_has_objc_copyRealizedClassList)
     return DynamicClassInfoExtractor::gdb_objc_realized_classes;
 
   if (Process *process = m_runtime.GetProcess()) {