* "arch/syscallent.h" is made from <asm/unistd.h>.
  It can be done automatically with "mksyscallent" for all the
  architectures except "mips" (as of linux-2.2.12)

* "arch/signalent.h" is made from <asm/signal.h>.
  It can be done automatically with "mksignalent" for all the
  architectures. (linux-2.2.12)

* s390 uses mksyscallent_s390, rather than mksyscallent

* NOTE: This does not currently work for cross-compilers; Maybe
  I should guess the architecture using `gcc -print-libgcc-file-name'
  instead of `uname -m' (or even better, use the value returned by autoconf)