x86 - AVX512 mask registers show up as invalid

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The next branch of Capstone doesn't seem to recognize the mask registers of x86's AVX512 extension any longer. For example:

$ kstool x64 'kmovw eax, k0'
kmovw eax, k0 = [ c5 f8 93 c0 ]
$ cstool -d x64 c5f893c0
 0  c5 f8 93 c0                                      kmovw      eax, k0
        ID: 288 (kmovw)
        Prefix:0x00 0x00 0x00 0x00 
        Opcode:0xc5 0xf8 0x00 0x00 
        rex: 0x40
        addr_size: 8
        modrm: 0xc0
        disp: 0x0
        sib: 0x0
        op_count: 2
                operands[0].type: REG = eax
                operands[0].size: 4
                operands[0].access: WRITE
                operands[1].type: REG = (null)
                operands[1].size: 0
                operands[1].access: READ
        Registers read: (null)
        Registers modified: eax
        Groups: avx512 

As you can see, Capstone gets the op_str correct, but fails to give the user operands[1].type, which is X86_REG_INVALID instead of X86_REG_K0.