Revert "Re-land r335297 "[X86] Implement more of x86-64 large and medium PIC code models""

Reverting because this is causing failures in the LLDB test suite on
GreenDragon.

  LLVM ERROR: unsupported relocation with subtraction expression, symbol
  '__GLOBAL_OFFSET_TABLE_' can not be undefined in a subtraction
  expression

llvm-svn: 335894