media-libs/cogl: Restore -f in rm -rvf

media-libs/cogl: Restore -f in rm -rvf

Because of the next patch we need to run eautoreconf, which somehow
causes this directory to not exist in the install. The -f was removed in
fc115d74f4ef ("media-libs/cogl: add missing mesa[egl] dep for USE=kms").
The commit message states

    Remove rm -f option usage while here (it makes the `|| die`
    useless and makes us not notice once this call isn't necessary
    anymore).

but cogl hasn't seen any real work in about three years, so I don't
think that's particularly important or likely to happen.

Bug: https://bugs.gentoo.org/692212
Signed-off-by: Matt Turner <mattst88@gentoo.org>