REORG: threads: move the struct thread_info from global.h to hathreads.h

It doesn't make sense to keep this struct thread_info in global.h, it
causes difficulties to access its contents from hathreads.h, let's move
it to the threads where it ought to have been created.
diff --git a/src/hathreads.c b/src/hathreads.c
index fc17318..2dbf467 100644
--- a/src/hathreads.c
+++ b/src/hathreads.c
@@ -29,6 +29,7 @@
 #include <types/global.h>
 #include <proto/fd.h>
 
+struct thread_info thread_info[MAX_THREADS];
 
 #ifdef USE_THREAD