plumb glibc clock_get interfaces to irt

elf/Versions

 libc {
   GLIBC_2.0 {
 %ifdef EXPORT_UNWIND_FIND_FDE
     __register_frame_info; __deregister_frame_info;
 %endif
   }
   GLIBC_2.1 {
     # functions used in other libraries
     _dl_mcount_wrapper; _dl_mcount_wrapper_check;
   }
@@ skipping 51 matching lines @@
     nacl_interface_query;
   }
   GLIBC_PRIVATE {
     # Futex emulation: used by libc and NPTL.
     __nacl_futex_wait;
     __nacl_futex_wake;
     __nacl_futex_wake_op;
     __nacl_futex_cmp_requeue;
     # Syscall table: can be used to intercept syscalls.
     __nacl_irt_clock;
+    __nacl_irt_clock_getres;
+    __nacl_irt_clock_gettime;
     __nacl_irt_close;
     __nacl_irt_cond_broadcast;
     __nacl_irt_cond_create;
     __nacl_irt_cond_destroy;
     __nacl_irt_cond_signal;
     __nacl_irt_cond_timed_wait_abs;
     __nacl_irt_cond_wait;
     __nacl_irt_dup2;
     __nacl_irt_dup;
     __nacl_irt_dyncode_create;
@@ skipping 34 matching lines @@
     _dl_allocate_tls; _dl_deallocate_tls;
     _dl_get_tls_static_info; _dl_allocate_tls_init;
     _dl_tls_setup; _dl_rtld_di_serinfo;
     _dl_make_stack_executable;
     # Only here for gdb while a better method is developed.
     _dl_debug_state;
     # Pointer protection.
     __pointer_chk_guard;
   }
 }