git-mailrc: Replace tabs with spaces in alias entries

patman's _ReadAliasFile only splits on spaces, not tabs, so the entries
for dinh and maxime weren't being recognised as valid. I'll fix patman
in a separate patch, but this makes all the entries consistent.

Signed-off-by: Adam Sampson <ats@offog.org>
Reviewed-by: Simon Glass <sjg@chromium.org>