reg-stack.c (subst_stack_regs_pat): Abort if the destination of a FP conditional move is not on the FP register stack.

        * reg-stack.c (subst_stack_regs_pat): Abort if the destination
        of a FP conditional move is not on the FP register stack.
Forgot to check it in last night/this morning.  One should not hack at 4am.

From-SVN: r24716