search for: 0b010101

Hi, We have a significant regression since llvm 5.0.0 in the x86 assembler. The following snippets fail: 1) .intel_syntax 0: jmp 0b 2) .intel_syntax and edi, 0b010101 when running through `llvm-mc -arch x86-64`. This regression was introduced in r301390, which was driven by PR27884. I think https://llvm.org/PR36144 describes this very well, and I think we should get this fixed, since it's a pretty basic thing to support in the assembler. Here are a few s...