gcc-plugins: Use dynamic initializers

commit b86729109c5fd0a480300f40608aac68764b5adf upstream.

GCC 8 changed the order of some fields and is very picky about ordering
in static initializers, so instead just move to dynamic initializers,
and drop the redundant already-zero field assignments.

Suggested-by: Valdis Kletnieks <valdis.kletnieks@vt.edu>
Signed-off-by: Kees Cook <keescook@chromium.org>
Cc: Lance Albertson <lance@osuosl.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>