Revert commit v3.13.0-rc1~441^2 (install: Teach CODE,SCRIPT modes to
evaluate generator expressions, 2018-05-29). Unfortunately it has
been found to break existing code in a real project, e.g.
install(CODE [[
message("$<FOOBAR>")
]])
Address this regression by reverting support for the 3.13 release
series. Support can be restored later with a policy for compatibility.
Issue: #15785Fixes: #18435
Found via `codespell -q 3 -I ../cmake-whitelist.txt --skip="./Utilities"`
where the whitelist consists of
```
aci
ans
behaviour
buil
convertor
dum
earch
ect
emmited
emmitted
helpfull
iff
isnt
ith
lowercased
mose
nd
nknown
nto
objext
ot
pathes
pevents
splitted
substract
superceded
supercedes
te
tim
todays
uint
upto
whitespaces
```
Brad King