emacsclient: sockaddr portability fixes

* lib-src/emacsclient.c (get_server_config, set_tcp_socket)
(set_local_socket): Initialize any platform-specific extensions
of struct to zero, just in case.
(set_tcp_socket, set_local_socket): Don’t assume struct
layout details that POSIX does not specify.
Use union to sidestep some problems with strict aliasing.
Remove unnecessary casts.
1 job for master in 22 minutes and 3 seconds (queued for 4 seconds)
Status Job ID Name Coverage
  Test
failed #122
test

00:22:03

 
Name Stage Failure
failed
test Test
Makefile:301: recipe for target 'check-doit' failed
make[2]: *** [check-doit] Error 1
make[2]: Leaving directory '/builds/tzz/emacs/test'
Makefile:271: recipe for target 'check' failed
make[1]: *** [check] Error 2
make[1]: Leaving directory '/builds/tzz/emacs/test'
Makefile:955: recipe for target 'check' failed
make: *** [check] Error 2
ERROR: Job failed: exit code 1