includes/std: Added std::mem::set_section_size (#175)

includes/std/mem.pat

@@ -180,6 +180,15 @@ namespace std::mem {
         return builtin::std::mem::get_section_size(section);
     };
 
+    /**
+        Changes the size of a custom section
+        @param section The handle to the section
+        @param size The new size of the section
+    */
+    fn set_section_size(Section section, u128 size) {
+        builtin::std::mem::set_section_size(section, size);
+    };
+
     /**
         Copies a range of bytes from one section into another
         @param from_section The section to copy from