Log Message:
protobuf-c: update to 1.4.0.

protobuf-c (1.4.0)

  [ Robert Edmonds ]
  * Release 1.4.0.

  [ Ilya Lipnitsky ]
  * c_message.cc: Resolve name conflict between certain enums and oneofs
    (#427).
  * protobuf-c.h: Fix Windows DLL export issue with the
    protobuf_c_empty_string symbol (#428).
  * Standardize pkg-config for use by autotools and cmake, fix cmake tests
    (#425).
  * protobuf-c.c: Cast %lu args to unsigned long int (#429).
  * protoc-c: Remove leading underscores from structs (#430).
  * protoc-c: Fix shared lib build on windows, migrate from Travis CI to
    GitHub Actions (#459).
  * protobuf-c: Don't use ProtobufCWireType internally (#463).
  * protoc-c: Add custom options support (#466).
  * protobuf-c.c: Fix packed repeated bool parsing (#467).

  [ Markus Engel ]
  * Pack nested messages inline (#431).

  [ Daniel Axtens ]
  * Travis CI: Test on other platforms (#438).

  [ Adam Cozzette ]
  * Update the generator to fully qualify std::string (#443).

  [ Piotr Pietraszkiewicz ]
  * Install MSVC debug symbols alongside the protobuf-c.lib file (#456).

  [ ihsinme ]
  * Fix invalid unsigned arithmetic (#455).

  [ Wolfram Rösler ]
  * Avoid "unused function parameter" compiler warning (#453).