Adding macro definitions for declaring C structures and pointers.

src/c_struct.rs

@@ -0,0 +1,18 @@
+/// Defines a C style structure.
+#[macro_export]
+macro_rules! c_struct
+{
+   {
+      $cname: ident
+      {
+         $($name: ident: $type: ty);*;
+      }
+   } =>
+   {
+      #[repr(C)]
+      pub struct $cname
+      {
+         $(pub $name: $type),+,
+      }
+   };
+}