Reorganize D modules a bit

src/hello/hello.d

@@ -1,6 +1,8 @@
+module hello.hello;
+
 import uefi;
-import output;
-import scratch;
+import hello.output;
+import hello.scratch;
 import hulk.bootinfo;
 import hos.page_table;
 import hos.cpu;

src/hello/output.d

@@ -1,5 +1,7 @@
+module hello.output;
+
 import uefi;
-import hello;
+import hello.hello;
 import core.stdc.stdarg;
 
 private size_t format_hex(CHAR16 * s, ulong v, bool ptr)

src/hello/scratch.d

@@ -1,3 +1,5 @@
+module hello.scratch;
+
 align(4096) __gshared ubyte[1024 * 1024] scratch;
 __gshared size_t scratch_used;