textproc/kf5-sonnet: unbreak with hunspell 1.5

• Could NOT find HUNSPELL (missing: HUNSPELL_LIBRARIES)

[...]

• The following OPTIONAL packages have not been found:
• HUNSPELL , Spell checking support via Hunspell , http://hunspell.sourceforge.net/

[...]

> Checking for items in pkg-plist which are not in STAGEDIR

Error: Missing: %%QT_PLUGINDIR%%/kf5/sonnet/hunspell.so

PR: 214837
Approved by: portmgr blanket