[PATCH] Emit a trap instruction for IR 'unreachable'

[Yaron Keren]

  code was cut off, trying again:

  `foo:                                    # @foo
  # BB#0:                                 # %entry
          leaq    _ZN11xercesc_2_56XMLUni16fgNotationStringE(%rip), %rax
          leaq    _ZN11xercesc_2_513SchemaSymbols21fgURI_SCHEMAFORSCHEMAE(%rip), %rcx
          orq     %rax, %rcx
          ud2

  `

http://reviews.llvm.org/D3417