message: Modify int64_t access operator for Signal
  Slight optimization which avoids signextending twice which happens when calling
  the int() operator.
diff: @@ -72,7 +72,7 @@ public:
  explicit operator int() const { return signextend<int32_t, n>(m_value); }
  explicit operator uint32_t() const { return m_value; }
  explicit operator uint64_t() const { return m_value; }
  - explicit operator int64_t() const { return signextend<int64_t, 32>(static_cast<int>(*this)); }
  + explicit operator int64_t() const { return signextend<int64_t, n>(m_value); }
  explicit operator bool() const { return m_value & 0b1; }
  Signal& operator=(const uint32_t& v) {
  