* dwarf2-frame.c (dwarf2_reg_rule): Add REG_RA and REG_CFA.

* dwarf2-frame.c (dwarf2_reg_rule): Add REG_RA and REG_CFA.
(dwarf2_frame_cache): Initialize PC_REGNUM with REG_RA and
SP_REGNUM with REG_CFA.  Don't overwrite the initialized register
rule for registers left unspecified by the CFI.  Remove the
special handling of PC_REGNUM.  Add code to eleminate any REG_RA
rules.
(dwarf2_frame_prev_register): Remove the special handling of
SP_REGNUM.  Add support for the REG_CFA rule.