Clean up linker script symbols

src/hulk/header.d

@@ -11,14 +11,14 @@ import hulk.bootinfo;
 struct HulkHeader
 {
     /**
-     * Total size of memory to be mapped.
+     * HULK BSS size.
+     *
+     * The OS loader must map memory to a zeroed range of this size.
      *
-     * The OS loader must ensure that virtual memory is mapped for this entire
-     * size.
      * This value is really an integer, but is stored as a pointer because it
      * is provided by the linker and LDC does not like us to cast it.
      */
-    void * total_size;
+    void * hulk_bss_size;
 
     /** Entry point. */
     void * entry;