Add platform defines header

Makefile.am

@@ -63,6 +63,7 @@ UTIL_FILES   =		\
     nocopy.hpp		\
     perlin.cpp		\
     perlin.hpp		\
+    platform.hpp	\
     point.cpp		\
     point.hpp		\
     pool.cpp		\

platform.hpp

@@ -0,0 +1,31 @@
+/*
+ * This file is part of libgim.
+ *
+ * libgim is free software: you can redistribute it and/or modify it under the
+ * terms of the GNU General Public License as published by the Free Software
+ * Foundation, either version 3 of the License, or (at your option) any later
+ * version.
+ *
+ * libgim is distributed in the hope that it will be useful, but WITHOUT ANY
+ * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+ * FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more
+ * details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with libgim.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ * Copyright 2010-2012 Danny Robson <danny@nerdcruft.net>
+ */
+
+#ifndef __UTIL_PLATFORM_HPP
+#define __UTIL_PLATFORM_HPP
+
+#if defined(__linux__) || defined (__linux)
+    #define PLATFORM_LINUX
+#elif defined(__WIN32) || defined (_WIN32)
+    #define PLATFORM_WIN32
+#else
+    #error "Unknown platform"
+#endif
+
+#endif