Create a build_config header file.

src/include/build_config.h

Index: src/include/build_config.h
diff --git a/src/include/build_config.h b/src/include/build_config.h
new file mode 100644
index 0000000000000000000000000000000000000000..f1c4736ef38688b9ffb3311c4865b0cb771f4514
--- /dev/null
+++ b/src/include/build_config.h
@@ -0,0 +1,79 @@
+/*
+ * Copyright 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.
+ */
+
+#ifndef NATIVE_CLIENT_SRC_INCLUDE_BUILD_CONFIG_H_
+#define NATIVE_CLIENT_SRC_INCLUDE_BUILD_CONFIG_H_ 1
+
+#include "native_client/src/include/nacl_base.h"
+
+#if !defined(NACL_WINDOWS) && !defined(NACL_LINUX) && !defined(NACL_OSX) && \
+    !defined(NACL_ANDROID)
+
+#if defined(_WIN32)
+# define NACL_WINDOWS 1
+#else
+# define NACL_WINDOWS 0
+#endif
+
+#if defined(__linux__)
+# define NACL_LINUX 1
+#else
+# define NACL_LINUX 0
+#endif
+
+#if defined(__APPLE__)
+# define NACL_OSX 1
+#else
+# define NACL_OSX 0
+#endif
+
+#if defined(ANDROID)
+# define NACL_ANDROID 1
+#else
+# define NACL_ANDROID 0
+#endif
+
+#endif
+
+/* TODO(teravest): Remove this guard when builds stop defining these. */
+#if defined(NACL_BUILD_ARCH) && (NACL_ARCH(NACL_BUILD_ARCH) != NACL_pnacl) && \
+    !defined(NACL_BUILD_SUBARCH)

[Mark Seaborn, 2015/01/07 20:52:39]

Indent to line up with "("

[Mark Seaborn, 2015/01/07 23:22:33]

Oops, sorry, my mistake.  I missed the closing ")" on the line before.

[teravest, 2015/01/08 17:17:13]

Removed the unnecessary parens around:
  NACL_ARCH(NACL_BUILD_ARCH) != NACL_pnacl

+# error Please define both NACL_BUILD_ARCH and NACL_BUILD_SUBARCH.
+#elif !defined(NACL_BUILD_ARCH) && defined(NACL_BUILD_SUBARCH)
+# error Please define both NACL_BUILD_ARCH and NACL_BUILD_SUBARCH.
+#endif
+
+
+#if !defined(NACL_BUILD_ARCH)
+
+#if defined(_M_X64) || defined(__x86_64__)
+# define NACL_BUILD_ARCH x86
+# define NACL_BUILD_SUBARCH 64
+#endif
+
+#if defined(_M_IX86) || defined(__i386__)
+# define NACL_BUILD_ARCH x86
+# define NACL_BUILD_SUBARCH 32
+#endif
+
+#if defined(__ARMEL__)
+# define NACL_BUILD_ARCH arm
+# define NACL_BUILD_SUBARCH 32
+#endif
+
+#if defined(__MIPSEL__)
+# define NACL_BUILD_ARCH mips
+# define NACL_BUILD_SUBARCH 32
+#endif
+
+#endif  /* !defined(NACL_BUILD_ARCH) */
+
+/*
+ * TODO(teravest): Require NACL_BUILD_ARCH and NACL_BUILD_SUBARCH to be defined
+ * once they're defined for the pnacl translator build.
+ */
+
+#endif  /* NATIVE_CLIENT_SRC_INCLUDE_BUILD_CONFIG_H_ */