the current code base assumes that all 64bit ports provide __NR_creat. this is done by sysdeps/unix/sysv/linux/wordsize-64/creat64.c being a stub which means the previous symbol location in io/creat64.c is not used. other 64bit ports use sysdeps/unix/sysv/linux/wordsize-64/syscalls.list to make creat64 an alias to the creat function, thus overriding the io/creat.c file. since alpha lacks __NR_creat, the creat line in syscalls.list is ignored, leaving alpha with io/creat.o declaring creat (and not creat64), and io/creat64.o declaring no symbols at all.
Alpha is not in the main tree anymore since we have no maintainer. Somebody has to step up and volunteer to be the maintainer of the alpha ports tree or nothing will happen.
Richard Henderson fixed this with commit c7b880234d5 to glibc-ports.git. Marking as fixed.