AArch64: Mark sve instructions that require MOVPRFX constraints
This patch series is to allow certain instructions such as the SVE MOVPRFX
instruction to apply a constraint/dependency on the instruction at PC+4.
This patch starts this off by marking which instructions impose the constraint
and which instructions must adhere to the constraint. This is done in a
generic way by extending the verifiers.
* The constraint F_SCAN indicates that an instruction opens a sequence and imposes
a constraint on an instructions following it. The length of the sequence depends
on the instruction itself and it handled in the verifier code.
* The C_SCAN_MOVPRFX flag is used to indicate which constrain the instruction is
checked against. An instruction with both F_SCAN and C_SCAN_MOVPRFX starts a
block for the C_SCAN_MOVPRFX instruction, and one with only C_SCAN_MOVPRFX must
adhere to a previous block constraint is applicable.
The SVE instructions in this list have been marked according to the SVE
specification[1].