editors/openoffice-*: Unbreak build on 15.0-CURRENT

Revert "editors/openoffice-*: Unbreak build on 15.0-CURRENT"

Undo the switch to llvm from ports.

This reverts commit f25b169ac89578f18a6e480d4d84284bb8085316.

Instead, pass --undefined-version to the linker to avoid the build
breakage on -CURRENT by the change to the default value for this
switch.

Tidy up LIB_DEPENDS.