Fix handling of "$@" (that is, double quoted dollar at), when it
appears in a string which will be subject to field splitting.
Eg:
${0+"$@" }
More common usages, like the simple "$@" or ${0+"$@"} end up
being entirely quoted, so no field splitting happens, and the
problem was avoided.
See the PR for more details.
This ends up making a bunch of old hack code (and some that was
relatively new) vanish - for now it is just #if 0'd or commented out.
Cleanups of that stuff will happen later.
That some of the worst $@ hacks are now gone does not mean that processing
of "$@" does not retain a very special place in every hackers heart.
RIP extreme ugliness - long live the merely ordinary ugly.
Added a new bin/sh ATF test case to verify that all this remains fixed.
265b061776