constants file

[Henry Cejtin]

I  would  say that 1 or 2 are the best.  The advantage of 1 over 2 is that if
some one changes, for instance, the kernel or glibc in  a  way  that  changes
these constants then the new generated executables will know about that.  The
disadvantage is that it makes compilation a bit longer (but probably  squat).

3  is markedly worse than 1 or 2.  It means that if some one installs the RPM
on a machine  with  a  different  glibc  or  kernel  reflected  in  different
constants  then  the  resulting compiled programs might not work.  Note, this
change has happened before with various glibc changes.  In  those  cases  the
old  shared  libraries  are  kept around (so that old executables continue to
work) but newly compiled stuff will use the new libraries, so that  would  be
bad for us.