[lldb/crashlog] Fix line entries resolution in interactive mode

This patch subtracts 1 to the pc of any frame above frame 0 to get the
previous line entry and display the right line in the debugger.

This also rephrase some old comment from `48d157dd`.

rdar://92686666

Differential Revision: https://reviews.llvm.org/D125928



Signed-off-by: Med Ismail Bennani <medismail.bennani@gmail.com>