rdar://problem/10712130

Fixed an issue where backtick char is not properly honored when setting the frame-format variable, like the following:

(lldb) settings set frame-format frame #${frame.index}: ${frame.pc}{ ${module.file.basename}{`${function.name-with-args}${function.pc-offset}}}{ at ${line.file.basename}:${line.number}}\n
(lldb) settings show frame-format
frame-format (string) = "frame #${frame.index}: ${frame.pc}{ `${module.file.basename}{${function.name-with-args}${function.pc-offset}}}{` at ${line.file.basename}:${line.number}}\n"
(lldb)

o CommandObjectSettings.h/.cpp:

  Modify the command object impl to require raw command string instead of parsed command string,
  which also fixes an outstanding issue that customizing the prompt with trailing spaces doesn't
  work.

o Args.cpp:

  During CommandInterpreter::HandleCommand(), there is a PreprocessCommand phase which already
  strips/processes pairs of backticks as an expression eval step.  There's no need to treat
  a backtick as starting a quote.

o TestAbbreviations.py and change_prompt.lldb:

  Fixed incorrect test case/logic.

o TestSettings.py:

  Remove expectedFailure decorator.

llvm-svn: 148491