Trailing whitespace

[johnsonjh]

The following (harmless, but useless) trailing whitespace was detected:

src/libbacktrace/dwarf.c:
        2042: Trailing whitespace
        2241: Trailing whitespace

src/libbacktrace/macho.c:
        677: Trailing whitespace

I noticed this integrating it into a project. I disabled checking libbacktrace in my pre-commit hook, but fixing it is trivial.

PR in #125.

[ianlancetaylor]

Thanks.