Correctly detect macOS devices when importing headers

Building rep on an M1 running macOS Ventura (13.1) fails: use of undeclared identifier 'IPPROTO_TCP' and friends.

A similar issue has been encountered in https://github.com/CopernicaMarketingSoftware/AMQP-CPP/issues/300. It appears that <netinet/in.h> is not imported correctly on Apple systems.

Full build output

``` @nix { "action": "setPhase", "phase": "unpackPhase" } unpacking sources unpacking source archive /nix/store/b9yc1an3xqlaq95lv68xhbya3wgzmazz-3dwlyr0v1asj925128izynm0iq7sqbnb-source source root is 3dwlyr0v1asj925128izynm0iq7sqbnb-source @nix { "action": "setPhase", "phase": "patchPhase" } patching sources @nix { "action": "setPhase", "phase": "updateAutotoolsGnuConfigScriptsPhase" } updateAutotoolsGnuConfigScriptsPhase @nix { "action": "setPhase", "phase": "configurePhase" } configuring no configure script, doing nothing @nix { "action": "setPhase", "phase": "buildPhase" } building build flags: SHELL=/nix/store/1xprix2z0194xyqgz0xk7id16pxn6yy6-bash-5.1-p16/bin/bash prefix=\$$out$ clang -g -O2 -o rep rep.c rep.c:406:17: warning: implicit declaration of function 'recv' is invalid in C99 [-Wimplicit-function-declaration] int count = recv(reader->fd, &ch, 1, 0); ^ rep.c:626:20: error: incomplete result type 'struct sockaddr_in' in function definition struct sockaddr_in options_address_from_file(struct options* options, const char* filename) ^ rep.c:610:8: note: forward declaration of 'struct sockaddr_in' struct sockaddr_in options_address(struct options* options, const char* port); ^ rep.c:631:12: error: calling 'options_address' with incomplete return type 'struct sockaddr_in' return options_address(options, linebuffer); ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ rep.c:610:20: note: 'options_address' declared here struct sockaddr_in options_address(struct options* options, const char* port); ^ rep.c:610:8: note: forward declaration of 'struct sockaddr_in' struct sockaddr_in options_address(struct options* options, const char* port); ^ rep.c:634:20: error: incomplete result type 'struct sockaddr_in' in function definition struct sockaddr_in options_address_from_relative_file(struct options* options, const char* directory_in, const char* filename) ^ rep.c:610:8: note: forward declaration of 'struct sockaddr_in' struct sockaddr_in options_address(struct options* options, const char* port); ^ rep.c:652:32: error: variable has incomplete type 'struct sockaddr_in' struct sockaddr_in result = options_address_from_file(options, path_to_check); ^ rep.c:610:8: note: forward declaration of 'struct sockaddr_in' struct sockaddr_in options_address(struct options* options, const char* port); ^ rep.c:686:20: error: incomplete result type 'struct sockaddr_in' in function definition struct sockaddr_in options_address(struct options* options, const char* port) ^ rep.c:610:8: note: forward declaration of 'struct sockaddr_in' struct sockaddr_in options_address(struct options* options, const char* port); ^ rep.c:695:28: error: variable has incomplete type 'struct sockaddr_in' struct sockaddr_in result = options_address_from_relative_file(options, absolute_directory, filename); ^ rep.c:610:8: note: forward declaration of 'struct sockaddr_in' struct sockaddr_in options_address(struct options* options, const char* port); ^ rep.c:702:23: error: use of undeclared identifier 'AF_INET' .sin_family = AF_INET, ^ rep.c:703:34: error: use of undeclared identifier 'INADDR_LOOPBACK' .sin_addr.s_addr = htonl(INADDR_LOOPBACK), ^ rep.c:703:34: error: use of undeclared identifier 'INADDR_LOOPBACK' rep.c:703:34: error: use of undeclared identifier 'INADDR_LOOPBACK' rep.c:703:34: error: use of undeclared identifier 'INADDR_LOOPBACK' rep.c:703:34: error: use of undeclared identifier 'INADDR_LOOPBACK' rep.c:703:34: error: use of undeclared identifier 'INADDR_LOOPBACK' rep.c:700:24: error: variable has incomplete type 'struct sockaddr_in' struct sockaddr_in address = ^ rep.c:610:8: note: forward declaration of 'struct sockaddr_in' struct sockaddr_in options_address(struct options* options, const char* port); ^ rep.c:719:35: warning: implicit declaration of function 'gethostbyname' is invalid in C99 [-Wimplicit-function-declaration] struct hostent *ent = gethostbyname(host_part); ^ rep.c:719:29: warning: incompatible integer to pointer conversion initializing 'struct hostent *' with an expression of type 'int' [-Wint-conversion] struct hostent *ent = gethostbyname(host_part); ^ ~~~~~~~~~~~~~~~~~~~~~~~~ rep.c:722:28: error: incomplete definition of type 'struct hostent' if (NULL == ent->h_addr) ~~~^ rep.c:719:20: note: forward declaration of 'struct hostent' struct hostent *ent = gethostbyname(host_part); ^ rep.c:727:53: error: incomplete definition of type 'struct hostent' address.sin_addr.s_addr = *(u_long *)ent->h_addr_list[0]; ~~~^ rep.c:719:20: note: forward declaration of 'struct hostent' struct hostent *ent = gethostbyname(host_part); ^ rep.c:947:17: warning: implicit declaration of function 'socket' is invalid in C99 [-Wimplicit-function-declaration] nrepl->fd = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP); ^ rep.c:947:24: error: use of undeclared identifier 'AF_INET' nrepl->fd = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP); ^ rep.c:947:33: error: use of undeclared identifier 'SOCK_STREAM' nrepl->fd = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP); ^ rep.c:947:46: error: use of undeclared identifier 'IPPROTO_TCP' nrepl->fd = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP); ^ rep.c:1037:9: warning: implicit declaration of function 'send' is invalid in C99 [-Wimplicit-function-declaration] if (send(nrepl->fd, message, length, 0) != length) ^ fatal error: too many errors emitted, stopping now [-ferror-limit=] 5 warnings and 20 errors generated. make: *** [Makefile:11: rep] Error 1 ```

eraserhd / rep

Correctly detect macOS devices when importing headers #30