* modules/cache/mod_socache_shmcb.c (socache_shmcb_init): Describe

  error better for anon shm failure case, fixing gcc 9 warning on
  passing NULL for '%s'.


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1858565 13f79535-47bb-0310-9956-ffa450edef68