community/R: drop obsolete patch
issue #8918 (closed) is fixed upstream (as from R 4.0.4), thanks to a report at https://bugs.r-project.org/show_bug.cgi?id=17970
issue #8918 (closed) is fixed upstream (as from R 4.0.4), thanks to a report at https://bugs.r-project.org/show_bug.cgi?id=17970