cilk_scope without braces fails to sync

[VoxSciurorum]

This test program

#include <stdio.h>
#include <unistd.h>

int main(int argc, char *argv[])
{
  cilk_scope for (int i = 0; i < argc; ++i)
    cilk_spawn { fprintf(stdout, "%s\n", argv[i]); usleep(100); }
  return 0;
}

crashes with an assertion failure when run on more than one thread:

cilk assertion failed: __cilkrts_synced(sf)

Adding braces around the body of the cilk_scope fixes the problem.

The usleep call is to make sure work is stolen.