Filter out repeated sections from the X86 disassembler modRMTable. Saves about ~43K from a released build. Unfortunately the disassembler tables are still upwards of 800K.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@191652 91177308-0d34-0410-b5e6-96231b3b80d8