More CFG branch merge lossage

[Richard Earnshaw <rearnsha at buzzard dot freeserve dot co dot uk>]

Jan,

Here's another bug that seems to be a result of your recent CFG merges.

On an ARM target (arm-netbsd/arm-elf), the following code will abort in 
verify_local_live_at_start() when called after sched2.

This is causing a bootstrap failure while building jcf-write.c

void foo(int);

void f (int a, int b, int c)
{
  int x;

  if (a)
    x = b > 0 ? 7 : 0;
  else
    x = c > 0 ? 9 : 0;

  foo(x);
}

Until reload is completed, the two asignement expressions are handled as 
if_then_else expressions.  After reload these are split into conditional 
execution insns.  The new feature seems to be that the false arms of both 
expressions are being merged and that this is sufficient to confuse the 
conditional-life tracking that we perform.

R.