(x86_64_linux_sigcontext_addr): Replace `sizeof (struct siginfo)' by LINUX_SIGINFO_SIZE.
* config/i386/x86-64linux.mt: New file. * config/i386/nm-x86_64.h: New file. * x86-64-linux-tdep.c: New file. * x86-64-linux-nat.c: New file. * x86-64-tdep.c: New file. * x86-64-tdep.h: New file. * config/djgpp/fnchange.lst: Add entries for x86_64-linux-tdep.c and x86_64-linux-nat.c * Makefile.in: Add x86_64-linux-tdep.o, x86_64-tdep.o, x86_64-linux-tdep.o, x86_64-nat.o, update dependencies.