Expose more regs in syscall ARM

[2over12]

No description provided.

[RyanGlScott]

I think the comments above ARMSyscall could stand to be revised a little after these changes. Currently, they are:

macaw/macaw-aarch32/src/Data/Macaw/ARM/Arch.hs

Lines 174 to 189 in 54af25d

	-- | Issue a system call
	--
	-- The intent is that the user provides a mapping from system call numbers to
	-- handlers in macaw-aarch32-symbolic, enabling the translation to crucible to
	-- replace this operation with a lookup + call to a function handle. By
	-- capturing all of the necessary registers as inputs and outputs here,
	-- uniform treatment is possible. See the x86 version for a more detailed
	-- account of the translation strategy.
	--
	-- The 'WI.W' is the immediate operand embedded in the opcode
	--
	-- The rest of the arguments are all of the registers that participate in the
	-- syscall protocol (at least on Linux). Arguments are passed in r0-r6, while
	-- the syscall number is in r7.
	--
	-- The system call can return up to two values (in r0 and r1)

The "Arguments are passed in r0-r6, while the syscall number is in r7" bit should be updated to clarify that this specifically applies to the Linux ABI, but that other GPRs are also included such that this can also be used for different ABIs where other registers are involved.