ASSERT "missing decode type" for Intel-style disassembly of MULX

When I set asm to Intel style in the ir_x86.c test, I get this failure:

  0x0000559864e859d8  c4 e3 7b f0 41 37 25 rorx   eax, dword ptr [rcx+0x37], 0x25
<Application /home/bruening/dr/git/build_x64_dbg_tests/suite/tests/bin/api.ir (82473) DynamoRIO usage error : missing decode type>
<Usage error: missing decode type (/home/bruening/dr/git/src/core/arch/x86/disassemble.c, line 235)

It seems to be on mulx since that's the next line in the default-mode output:

  0x0000564efa8e29d8  c4 e3 7b f0 41 37 25 rorx   0x37(%rcx)[4byte] $0x00000025 -> %eax
  0x0000564efa8e29df  c4 62 fb f6 49 37    mulx   0x37(%rcx)[8byte] %rdx -> %rax %r9

Assigning to @hgreving2304 because you will presumably hit this anyway with the binutils tests. Actually the binutils are already in place for non-AVX512 -- are they not testing Intel syntax and that's why this wasn't hit there?

Seems like we should have ir_x86.c go through all the opcodes two extra times with AT&T and Intel style for disassembly testing to at least catch such asserts?