Portability: HOST_NAME_MAX is not everywhere

[jimklimov]

Google shows this issue popping up in many other projects too. Not all systems follow the same set of standards, and/or need to define special macros to enable those. Alternately MAXHOSTNAMELEN can be used on some systems. Note that these can have different sizes (I've seen 64, 255 and 256 in different OS samples), so if the limit is used in protocol strings it can cause some fun...

  CXX      src/src_fty_info_selftest-fty_info_selftest.o
/tmp/FTY/.srcclone/SunOS-i86pc-czmq_3/fty-info/src/fty_info_server.cc:32:28: fatal error: bits/local_lim.h: No such file or directory
 #include <bits/local_lim.h>
                            ^
compilation terminated.
gmake[2]: *** [Makefile:1032: src/src_libfty_info_la-fty_info_server.lo] Error 1
../../../.srcclone/SunOS-i86pc-czmq_3/fty-info/src/ftyinfo.cc: In function 'ftyinfo_t* ftyinfo_new(topologyresolver_t*)':
../../../.srcclone/SunOS-i86pc-czmq_3/fty-info/src/ftyinfo.cc:157:39: error: 'HOST_NAME_MAX' was not declared in this scope
     char *hostname = (char *) malloc (HOST_NAME_MAX+1);
                                       ^
gmake[2]: *** [Makefile:1025: src/src_libfty_info_la-ftyinfo.lo] Error 1
gmake[2]: Target 'all-am' not remade because of errors.
gmake[2]: Leaving directory '/tmp/FTY/.build/SunOS-i86pc-czmq_3/fty-info'
gmake[1]: *** [Makefile:1174: all-recursive] Error 1
gmake[1]: Target 'all' not remade because of errors.