message: mysql_utils.cc: access EnvoyException by reference.
  Compilation fails because Envoy::EnvoyException values are caught by
  value. Change the catching to references to fix the issue.
  source/extensions/filters/network/mysql_proxy/mysql_utils.cc:100:27: error: catching polymorphic type 'class Envoy::EnvoyException' by value [-Werror=catch-value=]
diff: @@ -43,7 +43,7 @@ int BufferHelper::peekUint8(Buffer::Instance& buffer, uint64_t& offset, uint8_t&
  val = buffer.peekLEInt<uint8_t>(offset);
  offset += sizeof(uint8_t);
  return MYSQL_SUCCESS;
  - } catch (EnvoyException e) {
  + } catch (EnvoyException& e) {
  // buffer underflow
  return MYSQL_FAILURE;
  }
  @@ -54,7 +54,7 @@ int BufferHelper::peekUint16(Buffer::Instance& buffer, uint64_t& offset, uint16_
  val = buffer.peekLEInt<uint16_t>(offset);
  offset += sizeof(uint16_t);
  return MYSQL_SUCCESS;
  - } catch (EnvoyException e) {
  + } catch (EnvoyException& e) {
  // buffer underflow
  return MYSQL_FAILURE;
  }
  @@ -65,7 +65,7 @@ int BufferHelper::peekUint32(Buffer::Instance& buffer, uint64_t& offset, uint32_
  val = buffer.peekLEInt<uint32_t>(offset);
  offset += sizeof(uint32_t);
  return MYSQL_SUCCESS;
  - } catch (EnvoyException e) {
  + } catch (EnvoyException& e) {
  // buffer underflow
  return MYSQL_FAILURE;
  }
  @@ -97,7 +97,7 @@ int BufferHelper::peekLengthEncodedInteger(Buffer::Instance& buffer, uint64_t& o
  } else {
  return MYSQL_FAILURE;
  }
  - } catch (EnvoyException e) {
  + } catch (EnvoyException& e) {
  // buffer underflow
  return MYSQL_FAILURE;
  }
  