add initial CMake and Visual Studio build support

This moves the compatibility include files from include to
include/compat so we can use the awful MS C compiler
<../include/> trick to emulate the GNU #include_next extension.

This also removes a few old compat files we do not need anymore.

include/compat/machine/endian.h

@@ -0,0 +1,40 @@
+/*
+ * Public domain
+ * machine/endian.h compatibility shim
+ */
+
+#ifndef LIBCRYPTOCOMPAT_BYTE_ORDER_H_
+#define LIBCRYPTOCOMPAT_BYTE_ORDER_H_
+
+#if defined(_WIN32)
+
+#define LITTLE_ENDIAN  1234
+#define BIG_ENDIAN 4321
+#define PDP_ENDIAN	3412
+
+/*
+ * Use GCC and Visual Studio compiler defines to determine endian.
+ */
+#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
+#define BYTE_ORDER LITTLE_ENDIAN
+#else
+#define BYTE_ORDER BIG_ENDIAN
+#endif
+
+#elif defined(__linux__)
+#include <endian.h>
+
+#elif defined(__sun) || defined(_AIX) || defined(__hpux)
+#include <sys/types.h>
+#include <arpa/nameser_compat.h>
+
+#elif defined(__sgi)
+#include <standards.h>
+#include <sys/endian.h>
+
+#else
+#include_next <machine/endian.h>
+
+#endif
+
+#endif