(reload_reg_used_for_inherit): New variable.

(reload_reg_used_for_inherit): New variable.
(clear_reload_reg_in_use): New function.
(allocate_reload_reg): Don't consider an inherited register as one that we
should share in the first pass.
Don't mark a register in use until we are sure it will fit.
(choose_reload_regs): Mark spill regs used for inheriting.
When we decide we can no longer use a register, show it isn't being used.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@3991 138bc75d-0d04-0410-961f-82ee72b054a4