Add fsroot to fix linking issue

Author: jprendes

tools/fsroot.js

@@ -0,0 +1,63 @@
+/**
+ * @license
+ * Copyright 2013 The Emscripten Authors
+ * SPDX-License-Identifier: MIT
+ */
+
+mergeInto(LibraryManager.library, {
+  $FSROOT__deps: ["$FS"],
+  $FSROOT__postset: "FSROOT.staticInit();",
+  $FSROOT: {
+    staticInit: () => {
+      FS.root = null;
+
+      let opts = (Module.ROOT && Module.ROOT.opts) || {};
+      let type = (Module.ROOT && Module.ROOT.type) || "MEMFS";
+      if (typeof type === "string") {
+        type = FS.filesystems[type] || eval(type);
+      } else if (typeof type === "function") {
+        type = type(Module);
+      }
+      FS.mount(type, opts, '/');
+
+      FSROOT.createDefaultMountPoints();
+
+      // We need to ignore errors in mkdir
+      // since we are pre-creation mountpoints
+      // for directories otherwise created by the
+      // FS.create* functions
+      const restore_mkdir = FSROOT.safeMkdir();
+
+      FS.createDefaultDirectories();
+      FS.createDefaultDevices();
+      FS.createSpecialDirectories();
+
+      restore_mkdir();
+    },
+    createDefaultMountPoints: () => {
+      // Mount a new MEMFS for /dev
+      FS.mkdirTree("/dev");
+      FS.mount(MEMFS, {}, "/dev");
+
+      // Mount a new MEMFS for /proc/self
+      FS.mkdirTree('/proc/self');
+      FS.mount(MEMFS, {}, '/proc/self');
+    },
+    safeMkdir: () => {
+      const mkdir = FS.mkdir;
+      FS.mkdir = (path, mode) => {
+        try {
+          return mkdir(path, mode);
+        } catch {
+          // ignore errors
+          return FS.lookupPath(path, { follow: true }).node;
+        }
+      };
+      return () => {
+          FS.mkdir = mkdir;
+      };
+    },
+  },
+});
+
+DEFAULT_LIBRARY_FUNCS_TO_INCLUDE.push('$FSROOT');