Silence implicit fallthrough warning on newer GCC versions

[esabol]

In my testing on Alpine 3.13 (which has gcc 10.2.1) and 3.17 (which has gcc 12.2.1), the following warning was printed during the builds:

  CXX      libgearman-server/plugins/protocol/http/libgearman_server_la-protocol.lo
libgearman-server/plugins/protocol/http/protocol.cc: In member function 'virtual size_t HTTPtext::pack(const gearmand_packet_st*, gearman_server_con_st*, void*, size_t, gearmand_error_t&)':
libgearman-server/plugins/protocol/http/protocol.cc:153:25: warning: this statement may fall through [-Wimplicit-fallthrough=]
  153 |       gearmand_log_debug(GEARMAN_DEFAULT_LOG_PARAM,
      |       ~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~
  154 |                          "Bad packet command: gearmand_command_t:%s",
      |                          ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  155 |                          gearman_strcommand(packet->command));
      |                          ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
libgearman-server/plugins/protocol/http/protocol.cc:157:5: note: here
  157 |     case GEARMAN_COMMAND_WORK_FAIL:
      |     ^~~~

This pull request address this by ignoring -Wimplicit-fallthrough in libgearman-server/plugins/protocol/http/protocol.cc.

I used a variation on the Dockerfile in this comment with the modified server.cc file to test these changes.

[SpamapS]

Wow quite the pragma block