[NaCl SDK} Add EventListener and EventEmitter to support epoll.

native_client_sdk/src/libraries/nacl_io/library.dsc

 {
   'TOOLS': ['newlib', 'glibc', 'pnacl', 'win'],
   'SEARCH': [
     '.',
     'pepper'
   ],
   'TARGETS': [
     {
       'NAME' : 'nacl_io',
       'TYPE' : 'lib',
       'SOURCES' : [
+        "event_emitter.cc",
+        "event_listener.cc",
         "kernel_handle.cc",
         "kernel_intercept.cc",
         "kernel_object.cc",
         "kernel_proxy.cc",
         "kernel_wrap_glibc.cc",
         "kernel_wrap_newlib.cc",
         "kernel_wrap_win.cc",
         "mount.cc",
         "mount_dev.cc",
         "mount_html5fs.cc",
         "mount_http.cc",
         "mount_mem.cc",
         "mount_node.cc",
         "mount_node_dir.cc",
         "mount_node_html5fs.cc",
         "mount_node_http.cc",
         "mount_node_mem.cc",
         "mount_passthrough.cc",
         "nacl_io.cc",
         "path.cc",
         "pepper_interface.cc",
         "real_pepper_interface.cc",
       ],
     }
   ],
   'HEADERS': [
     {
       'FILES': [
+        "event_emitter.h",
+        "event_listener.h",
         "error.h",
         "inode_pool.h",
         "ioctl.h",
         "kernel_handle.h",
         "kernel_intercept.h",
         "kernel_object.h",
         "kernel_proxy.h",
         "kernel_wrap.h",
         "kernel_wrap_real.h",
         "mount.h",
@@ skipping 28 matching lines @@
         "all_interfaces.h",
         "define_empty_macros.h",
         "undef_macros.h",
       ],
       'DEST': 'include/nacl_io/pepper',
     }
   ],
   'DEST': 'src',
   'NAME': 'nacl_io',
 }