Empty ungotten chars for all filesystems when llseeking

src/library_fs.js

@@ -1068,7 +1068,9 @@ mergeInto(LibraryManager.library, {
       if (!stream.seekable || !stream.stream_ops.llseek) {
         throw new FS.ErrnoError(ERRNO_CODES.ESPIPE);
       }
-      return stream.stream_ops.llseek(stream, offset, whence);
+      stream.position = stream.stream_ops.llseek(stream, offset, whence);
+      stream.ungotten = [];
+      return stream.position;
     },
     read: function(stream, buffer, offset, length, position) {
       if (length < 0 || position < 0) {

src/library_memfs.js

@@ -335,8 +335,6 @@ mergeInto(LibraryManager.library, {
         if (position < 0) {
           throw new FS.ErrnoError(ERRNO_CODES.EINVAL);
         }
-        stream.ungotten = [];
-        stream.position = position;
         return position;
       },
       allocate: function(stream, offset, length) {

src/library_nodefs.js

@@ -279,7 +279,6 @@ mergeInto(LibraryManager.library, {
           throw new FS.ErrnoError(ERRNO_CODES.EINVAL);
         }
 
-        stream.position = position;
         return position;
       }
     }