Linux sandbox: modify GYP files to compile under Android.

sandbox/linux/seccomp-bpf/syscall_unittest.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include <asm/unistd.h>
 #include <fcntl.h>
 #include <sys/mman.h>
+#include <sys/syscall.h>
 #include <unistd.h>
 
 #include <vector>
 
 #include "base/basictypes.h"
 #include "base/posix/eintr_wrapper.h"
 #include "sandbox/linux/seccomp-bpf/bpf_tests.h"
 #include "sandbox/linux/seccomp-bpf/sandbox_bpf.h"
 #include "sandbox/linux/seccomp-bpf/syscall.h"
 #include "sandbox/linux/tests/unit_tests.h"
@@ skipping 157 matching lines @@
   EXPECT_EQ(8192, SandboxSyscall(__NR_read, fd, buf, 8192L));
   EXPECT_EQ(0, memcmp(addr2, buf, 8192));
 
   // Clean up
   EXPECT_EQ(0, SandboxSyscall(__NR_munmap, addr2, 8192L));
   EXPECT_EQ(0, SandboxSyscall(__NR_munmap, addr3, 4096L));
   EXPECT_EQ(0, HANDLE_EINTR(SandboxSyscall(__NR_close, fd)));
 }
 
 } // namespace