Add custom pm sysmodule

sysmodules/pm/source/exheader_info_heap.h

@@ -0,0 +1,9 @@
+#pragma once
+
+#include <3ds/exheader.h>
+
+// Official PM uses an overly complicated allocator with semaphores
+
+void ExHeaderInfoHeap_Init(void *buf, size_t num);
+ExHeader_Info *ExHeaderInfoHeap_New(void);
+void ExHeaderInfoHeap_Delete(ExHeader_Info *data);