dwarf2: store the RA state in CFI row

dwarf2: store the RA state in CFI row

On AArch64, the RA state informs the unwinder whether the return address
is mangled and how, or not. This information is encoded in a boolean in
the CFI row. This binary approach prevents from expressing more complex
configuration, as it is the case with PAuth_LR introduced in Armv9.5-A.

This patch addresses this limitation by replacing the boolean by an enum.

gcc/ChangeLog:

	* dwarf2cfi.cc
	(struct dw_cfi_row): Declare a new enum type to replace ra_mangled.
	(cfi_row_equal_p): Use ra_state instead of ra_mangled.
	(dwarf2out_frame_debug_cfa_negate_ra_state): Same.
	(change_cfi_row): Same.