Improve generation of conditional compares in gcc.

One of the problems with reducing BRANCH_COST is the loss in ability to do conditional compares as the generation of this relies on a code sequence produced by a high value of BRANCH_COST. An example of this is in the following testcase.

int foo (int x, int y,int z)
{
  if ( x == y || x == z)
   return 5;
  else
    return 10;
}

The output difference between -mcpu=cortex-a5 and -mcpu=cortex-a9 will explain what I'm referring to here.