Add build_config_functions.h to avoid #ifdef

sandbox/linux/seccomp-bpf/sandbox_bpf_unittest.cc

Index: sandbox/linux/seccomp-bpf/sandbox_bpf_unittest.cc
diff --git a/sandbox/linux/seccomp-bpf/sandbox_bpf_unittest.cc b/sandbox/linux/seccomp-bpf/sandbox_bpf_unittest.cc
index 9d67db8155336597c72ab8ef1b3a28963d7aa45a..835ad8eb17548ee642c9de4b4f9beace422eda18 100644
--- a/sandbox/linux/seccomp-bpf/sandbox_bpf_unittest.cc
+++ b/sandbox/linux/seccomp-bpf/sandbox_bpf_unittest.cc
@@ -22,6 +22,7 @@
 
 #include "base/memory/scoped_ptr.h"
 #include "build/build_config.h"
+#include "build/build_config_functions.h"
 #include "sandbox/linux/seccomp-bpf/bpf_tests.h"
 #include "sandbox/linux/seccomp-bpf/syscall.h"
 #include "sandbox/linux/seccomp-bpf/trap.h"
@@ -259,7 +260,7 @@ BPF_TEST(SandboxBpf, ErrnoTest, ErrnoTestPolicy) {
   // On Android, errno is only supported up to 255, otherwise errno
   // processing is skipped.
   // We work around this (crbug.com/181647).
-  if (sandbox::IsAndroid() && setgid(0) != -1) {
+  if (IsAndroid() && setgid(0) != -1) {
     errno = 0;
     BPF_ASSERT(setgid(0) == -ErrorCode::ERR_MAX_ERRNO);
     BPF_ASSERT(errno == 0);