Dispense with the FuncUndefined/CmdUndefined quasi-optimization.
If there are no rplugins, plugin/rplugin.vim takes less than 1ms.
Closes#5821Closes#6250
Helped-by: Qiming zhao <chemzqm@gmail.com>
It is otherwise impossible to determine which test failed sanitizer/valgrind
check. test/functional/helpers.lua module return was changed so that tests which
do not provide after_each function to get new check will automatically fail.