fix WasmFS API

Author: dschuff

src/library_wasmfs.js

@@ -198,7 +198,7 @@ FS.init();
 
       var bytesRead;
       if (seeking) {
-        bytesRead = __wasmfs_pread(stream.fd, dataBuffer, length, position);
+        bytesRead = __wasmfs_pread(stream.fd, dataBuffer, length, {{{ splitI64('position') }}});
       } else {
         bytesRead = __wasmfs_read(stream.fd, dataBuffer, length);
       }
@@ -222,7 +222,7 @@ FS.init();
 
       var bytesRead;
       if (seeking) {
-        bytesRead = __wasmfs_pwrite(stream.fd, dataBuffer, length, position);
+        bytesRead = __wasmfs_pwrite(stream.fd, dataBuffer, length, {{{ splitI64('position') }}});
       } else {
         bytesRead = __wasmfs_write(stream.fd, dataBuffer, length);
       }