Added irt extension support for supplying the nacl_irt_memory interface.

tests/irt_ext/nacl.scons

 # -*- python -*-
 # Copyright (c) 2014 The Native Client Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 Import('env')
 
 # IRT extensions test
 
 # TODO(dyen): Currently IRT extensions only supports newlib.
 if env.Bit('bitcode') or env.Bit('nacl_glibc'):
   Return()
 
 IRT_EXT_TEST_SRCS = [
     'error_report.c',
     'file_desc.c',
+    'mem_calls.c',
     ]
 
 IRT_EXT_LIBC_TEST_SRCS = [
     'libc/file_tests.c',
     'libc/libc_test.c',
+    'libc/mem_tests.c',
     ]
 
 irt_ext_libc_test_nexe = env.ComponentProgram('irt_ext_libc_test',
                                               (IRT_EXT_TEST_SRCS +
                                                IRT_EXT_LIBC_TEST_SRCS),
                                               EXTRA_LIBS=['${NONIRT_LIBS}'],
                                               )
 
 node = env.CommandSelLdrTestNacl('irt_ext_libc_test.out',
                                  irt_ext_libc_test_nexe)
 
 env.AddNodeToTestSuite(node, ['small_tests'],
                        'run_irt_ext_libc_test')