Targets such as rs6000-aix and alpha-vms that have unusual archive formats can't enable plugin support, because doing so makes ar create the wrong type of archive.
The master branch has been updated by Alan Modra <amodra@sourceware.org>: https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=1e92785005ce880a5fac9d022f05cdcff91c3091 commit 1e92785005ce880a5fac9d022f05cdcff91c3091 Author: Alan Modra <amodra@gmail.com> Date: Sun Jun 21 20:54:24 2020 +0930 PR26132, ar creates invalid libraries for some targets with plugins enabled PR 26132 * configure.ac: Disable plugins by default for some targets. * plugin.c: Comment typo fix. * configure: Regenerate.
git commit 0381901e629115 is a prerequisite for comment #1.