Remove code beads

[0x59616e]

TL;DR

The new disassembler cf0b6df6dbf5 has been commited, it's time to remove code beads.

Details

Code bead is the old encoding mechanism for M68k. Since now we have a new one, it's useless and we need to remove it.
I did a quick look through, we may need to modify these files (including but not limited to):

• llvm/lib/Target/M68k/CMakeLists.txt
  Just remove the tablegen(.... -gen-code-bead) line.

• llvm/lib/Target/M68k/M68kInstrFormats.td
  I think this one is the biggest one. It has tons of codebead-related code and comments.

• llvm/lib/Target/M68k/M68kInstrInfo.cpp

• llvm/lib/Target/M68k/MCTargetDesc/M68kMCCodeEmitter.cpp
  These two has some codebead-related code. Not a big problem

• llvm/utils/TableGen/CMakeLists.txt

• llvm/utils/TableGen/CodeBeadsGen.cpp
  Delete this one

• llvm/utils/TableGen/TableGen.cpp
  Remove the switch case.

[llvmbot]

@llvm/issue-subscribers-backend-m68k

[RKSimon]

Candidate Patch: https://reviews.llvm.org/D126349

[RKSimon]

@0x59616e - ok to close this?

[0x59616e]

Not yet. We still have lots of outdated tablegen code.

[0x59616e]

The lingering codebeads part in M68kInstrFormats.rd has been removed : 1290d0d.