Debugger: Add missing breaks in switch statements

Detected by GCC7

Change-Id: Ic4a1f0adac486d3f6d0f7da15b24e983c17225f3
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

src/plugins/debugger/debuggerprotocol.cpp

@@ -660,6 +660,7 @@ QString decodeData(const QString &ba, const QString &encoding)
                 union { char c[8]; double d; } u = {{s[7], s[6], s[5], s[4], s[3], s[2], s[1], s[0]}};
                 return QString::number(u.d);
             }
+            break;
         }
         case DebuggerEncoding::IPv6AddressAndHexScopeId: { // 16 hex-encoded bytes, "%" and the string-encoded scope
             const int p = ba.indexOf('%');

src/plugins/debugger/qml/qmlcppengine.cpp

@@ -630,6 +630,7 @@ void QmlCppEngine::slaveEngineStateChanged
                 case InferiorRunRequested:
                     // can happen if qml engine was active
                     notifyInferiorRunFailed();
+                    break;
                 default:
                     CHECK_STATE(InferiorStopOk);
                     break;

src/plugins/debugger/registerhandler.cpp

@@ -526,6 +526,7 @@ QVariant RegisterItem::data(int column, int role) const
                     return m_reg.value.toString(m_reg.kind, m_reg.size, m_format);
                 }
             }
+            break;
 
         case Qt::ToolTipRole:
             return QString("Current Value: %1\nPreviousValue: %2")
@@ -577,6 +578,7 @@ QVariant RegisterSubItem::data(int column, int role) const
                     return ba;
                 }
             }
+            break;
 
         case Qt::ToolTipRole:
             if (m_subKind == IntegerRegister) {
@@ -773,6 +775,7 @@ QVariant RegisterEditItem::data(int column, int role) const
                             .toString(m_subKind, m_subSize, m_subFormat, role == Qt::EditRole);
                 }
             }
+            break;
         case Qt::ToolTipRole: {
                 RegisterItem *registerItem = parent()->parent();
                 return RegisterHandler::tr("Edit bits %1...%2 of register %3")