re PR libgomp/64635 (darwin produces libgomp-plugin-host_nonshm.1.dylib but tries to load libgomp-plugin-host_nonshm.so.1)

        PR libgomp/64635
        * configure.tgt (*-*-aix*): Use standard posix plugin-suffix.h.
        Link with -lpthread.
        * config/aix/plugin-suffix.h: Delete.

From-SVN: r220341