Add libunwind build script

Not functionnal yet

libunwind-0002.patch

@@ -0,0 +1,25 @@
+From 9d0332b9dac6c5925c827d8b372f3c846da8a639 Mon Sep 17 00:00:00 2001
+From: =?UTF-8?q?Hugo=20Beauz=C3=A9e-Luyssen?= <hugo@beauzee.fr>
+Date: Fri, 13 May 2016 15:07:26 +0200
+Subject: [PATCH] Define _Unwind_Ptr on windows
+
+---
+ src/AddressSpace.hpp | 2 ++
+ 1 file changed, 2 insertions(+)
+
+diff --git a/src/AddressSpace.hpp b/src/AddressSpace.hpp
+index ab17d42..8e5fc20 100644
+--- a/src/AddressSpace.hpp
++++ b/src/AddressSpace.hpp
+@@ -47,6 +47,8 @@ extern "C" _Unwind_Ptr __gnu_Unwind_Find_exidx(_Unwind_Ptr addr, int *len);
+ // Emulate the BSD dl_unwind_find_exidx API when on a GNU libdl system.
+ #define dl_unwind_find_exidx __gnu_Unwind_Find_exidx
+ 
++#elif defined(_WIN32)
++typedef void *_Unwind_Ptr;
+ #elif !defined(_LIBUNWIND_IS_BAREMETAL)
+ #include <link.h>
+ #else // !defined(_LIBUNWIND_IS_BAREMETAL)
+-- 
+2.8.1
+