I started from tabs that are not on the beginning of lines, and in
several places I did further cleanings.
If you're worried about knowing who wrote some code, for example, if you
get to this commit in "git blame", then note that you can use the "-w"
flag in many git commands to ignore whitespaces. For example, to see
per-line authors, use "git blame -w <file>". Another example: to see
the (*much* smaller) non-whitespace changes in this (or any other)
commit, use "git log -p -w -1 <sha1>".
The target of the change is actually `hack-argument-replacement' in
`mred/private/coco/queue'. The replaced method can get called in
a different OS-level thread than the main thread.
Closes PR 12086
