[llvm-symbolizer] Add `--output-style` switch.

In general, llvm-symbolizer follows the output style of GNU's addr2line.
However, there are still some differences; in particular, for a requested
address, llvm-symbolizer prints line and column, while addr2line prints
only the line number.

This patch adds a new switch to select the preferred style.

Differential Revision: https://reviews.llvm.org/D60190

llvm-svn: 357675