arm: Use DWARF numbering convention for pseudo-register representation
This patch modifies the internal `struct reg_entry' numbering of DWARF
pseudo-registers to match values assigned in DWARF standards (see "4.1
DWARF register names" in [1])so ra_auth_code goes from 12 to 143 and
amends the unwinder .save directive-processing code to correctly handle
mixed register-type save directives.
The mechanism for splitting the register list is also re-written to
comply with register ordering on push statements, being that registers
are stored on the stack in numerical order, with the lowest numbered
register at the lowest address [2].
Consequently, the parsing of the hypothetical directive
.save{r4-r7, r10, ra_auth_core, lr}
has been changed such as rather than producing
.save{r4-r7, r10}
.save{ra_auth_code}
.save{lr}
as was the case with previous implementation, now produces: