Some of the --debug-* options can take an optional offset. Although the
man page does a good job of making that clear, it's much harder to
discover from the help output.
Currently the only reference to this is the following sentence:
> Where applicable these parameters take an optional =<offset> argument
> to dump only the entry at the specified offset.
This patch changes the help output from to print [=<offset>] after the
options that take an offset.
--debug-info[=<offset>] - Dump the .debug_info section
rdar://problem/63150066
Differential revision: https://reviews.llvm.org/D80959