Unlike Release build type, RelWithDebInfo does not disable asserts.
This helps get better debug info from people brave enough to use the
nightly builds, but shouldn't be used for official releases.
[skip ci]
In https://github.com/neovim/neovim/issues/14150 , investigations showed
that using an older gcc to build the appimage could result in severe
perf issues. This is because older gcc versions happily replace calls to
libc functions with their own, which happen to be less optimized than
their libc counterparts.
We fix this problem by upgrading to gcc-11 on ubuntu-18.04.
This reverts #13733. Disabling delete of the release leaves behind a
draft release associated with the previous nightly tag, which is
annoying to cleanup.
In the rare circumstances that the creation of a new nightly fails after
deleting the previous nightly, the job can be re-run or a nightly can be
missing for a day.
Assuming the `CMAKE_BUILD_TYPE` directive is case-sensitive, this *actually* prevents the nightly build from being optimized. Even if it doesn't, the typo causes `:checkhealth` to issue a dummy warning in the Performance section.
