Compiling for Snow Leopard

[startergo]

Is there anyway I can compile it for SL with Xcode 4.2 i686-apple-darwin10-llvm-gcc-4.2 (GCC) 4.2.1 or just the macserial.c?
tried even gcc5:

/opt/local/bin/gcc-mp-5 -o macserial macserial.c
Undefined symbols for architecture x86_64:
  "_main", referenced from:
      start in crt1.10.6.o
  "_IORegistryEntryCreateCFProperty", referenced from:
      _get_ioreg_entry in ccXk0B7T.o
  "_kIOMasterPortDefault", referenced from:
      _get_ioreg_entry in ccXk0B7T.o
  "_kCFAllocatorDefault", referenced from:
      _get_ioreg_entry in ccXk0B7T.o
  "_CFStringGetCStringPtr", referenced from:
      _get_ioreg_entry in ccXk0B7T.o
      _get_system_info in ccXk0B7T.o
  "_CFDataGetBytePtr", referenced from:
      _get_current_model in ccXk0B7T.o
      _get_system_info in ccXk0B7T.o
  "_pseudo_random_between", referenced from:
      _get_serial in ccXk0B7T.o
      _get_mlb in ccXk0B7T.o
  "_pseudo_random", referenced from:
      _get_production_year in ccXk0B7T.o
      _get_mlb in ccXk0B7T.o
  "_CFDataGetLength", referenced from:
      _get_current_model in ccXk0B7T.o
      _get_system_info in ccXk0B7T.o
  "_IORegistryEntryFromPath", referenced from:
      _get_ioreg_entry in ccXk0B7T.o
  "_IOObjectRelease", referenced from:
      _get_ioreg_entry in ccXk0B7T.o
  "_CFRelease", referenced from:
      _get_ioreg_entry in ccXk0B7T.o
      _get_current_model in ccXk0B7T.o
      _get_system_info in ccXk0B7T.o
  "___CFConstantStringClassReference", referenced from:
      CFString in ccXk0B7T.o
      CFString in ccXk0B7T.o
      CFString in ccXk0B7T.o
      CFString in ccXk0B7T.o
      CFString in ccXk0B7T.o
      CFString in ccXk0B7T.o
      CFString in ccXk0B7T.o
      ...
  "_CFStringGetTypeID", referenced from:
      _get_system_info in ccXk0B7T.o
  "_CFDataGetTypeID", referenced from:
      _get_current_model in ccXk0B7T.o
      _get_system_info in ccXk0B7T.o
  "_CFGetTypeID", referenced from:
      _get_ioreg_entry in ccXk0B7T.o
ld: symbol(s) not found for architecture x86_64
collect2: error: ld returned 1 exit status