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.

patches/opensslconf.h.patch

@@ -0,0 +1,13 @@
+--- include/openssl/opensslconf.h.orig	2015-07-19 23:21:47.000000000 -0600
++++ include/openssl/opensslconf.h	2015-07-19 23:21:17.000000000 -0600
+@@ -1,6 +1,10 @@
+ #include <openssl/opensslfeatures.h>
+ /* crypto/opensslconf.h.in */
+
++#if defined(_MSC_VER) && !defined(__attribute__)
++#define __attribute__(a)
++#endif
++
+ /* Generate 80386 code? */
+ #undef I386_ONLY
+