+ avoid macSpell var
I'm not sure to retrieve [NSSpellChecker sharedSpellChecker] in a pointer
is a good idea.
Most of the examples using sharedSpellChecker just call [NSSpellChecker sharedSpellChecker]
each time. If there's a bit more code, at least we're sure we won't leak because of this.

Change-Id: I9818bd3d51f26b50849e1a5e69cc705acd92ad29
Reviewed-on: https://gerrit.libreoffice.org/43140Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Julien Nabet <serval2412@yahoo.fr>