Fix native-comp warnings in *.el files

[Hi-Angel]

~There may be warnings in other files, I didn't look at those.~ I noticed two warnings in .yas-setup.el files, so decided to fix them; and I fixed warnings everywhere while at it 😊

The fact that everything compiles now without warnings was checked by a command:

emacs -batch --eval "(package-initialize) (setq byte-compile-error-on-warn t)" -f batch-byte-compile $(fnfx .el)

That revealed one doc-string warning, which I fixed in a separate commit.

[Hi-Angel]

Ping

[Hi-Angel]

Ping

[AndreaCrotti]

Nice thanks