MDEV-24841: More workarounds

For some reason, the tests of the MemorySanitizer build on 10.5 failed
with both clang 13 and clang 14 with SIGSEGV. On 10.6 where it worked
better, some more places to work around were identified.

mysys/my_lib.c

@@ -332,6 +332,13 @@ int my_fstat(File Filedes, MY_STAT *stat_area,
   DBUG_PRINT("my",("fd: %d  MyFlags: %lu", Filedes, MyFlags));
 #ifdef _WIN32
   DBUG_RETURN(my_win_fstat(Filedes, stat_area));
+#elif defined HAVE_valgrind
+  {
+    int s= fstat(Filedes, stat_area);
+    if (!s)
+      MSAN_STAT_WORKAROUND(stat_area);
+    DBUG_RETURN(s);
+  }
 #else
   DBUG_RETURN(fstat(Filedes, (struct stat *) stat_area));
 #endif

storage/myisam/mi_info.c

@@ -87,7 +87,10 @@ int mi_status(MI_INFO *info, register MI_ISAMINFO *x, uint flag)
     x->index_file_name  = share->index_file_name;
   }
   if ((flag & HA_STATUS_TIME) && !mysql_file_fstat(info->dfile, &state, MYF(0)))
+  {
+    MSAN_STAT_WORKAROUND(&state);
     x->update_time=state.st_mtime;
+  }
   else
     x->update_time=0;
   if (flag & HA_STATUS_AUTO)