[Bug testsuite/91065] New: gcc.dg/plugin/start_unit_plugin.c uses ggc memory without registering a root_tab

[amylaar at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91065

            Bug ID: 91065
           Summary: gcc.dg/plugin/start_unit_plugin.c uses ggc memory
                    without registering a root_tab
           Product: gcc
           Version: 10.0
            Status: UNCONFIRMED
          Keywords: GC
          Severity: normal
          Priority: P3
         Component: testsuite
          Assignee: unassigned at gcc dot gnu.org
          Reporter: amylaar at gcc dot gnu.org
  Target Milestone: ---
              Host: x86_64-pc-linux-gnu (probably doesn't really matter)
            Target: native or cross

gcc.dg/plugin/start_unit_plugin.c isets fake_var to ggc-allocated memory,
without registering a root_tab that references fake_var.
This causes gcc.dg/plugin/start_unit-test-1.c to fail when the compiler is
configured with --enable-checking=all