Define acpi structs as static

src/hulk/acpi.d

@@ -12,7 +12,7 @@ struct acpi
     enum uint APIC_SIGNATURE = 0x43495041u;
     enum uint XSDT_SIGNATURE = 0x54445358u;
 
-    struct XsdtHeader
+    static struct XsdtHeader
     {
         uint signature;
         uint length;
@@ -23,16 +23,16 @@ struct acpi
         uint oem_revision;
         uint creator_id;
         uint creator_revision;
-    };
+    }
 
-    struct Xsdt
+    static struct Xsdt
     {
         XsdtHeader header;
         uint _pad;
         ulong[0] tables;
     }
 
-    struct MadtHeader
+    static struct MadtHeader
     {
         uint signature;
         uint length;
@@ -47,7 +47,7 @@ struct acpi
         uint flags;
     }
 
-    struct MadtEntry
+    static struct MadtEntry
     {
         ubyte type;
         ubyte length;