abiword: make build deterministic for meta-office [1] in layers

The conditional DEPENDS was added for opendocument-plugin. Problem solving this
by PACKAGECONFIG is that --enable-plugins enables all plugins. Changing that to
--enable-plugins=<list of plugins> is a list which needs maintenance for future
versions of abiword. The change affects users adding meta-office in their
layers only. These tend to building libreoffice which DEPENDS on the additional
DEPENDS set her anyway - so there is not much additional build for these users.

[1] https://github.com/schnitzeltony/meta-office



Signed-off-by: Andreas Müller <schnitzeltony@googlemail.com>
Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>