Header refactoring: tsd - cleanup and dependency breaking.

This removes the tsd macros (which are used only for tsd_t in real builds).  We
break up the circular dependencies involving tsd.

We also move all tsd access through getters and setters.  This allows us to
assert that we only touch data when tsd is in a valid state.

We simplify the usages of the x macro trick, removing all the customizability
(get/set, init, cleanup), moving the lifetime logic to tsd_init and tsd_cleanup.
This lets us make initialization order independent of order within tsd_t.

include/jemalloc/internal/jemalloc_internal_externs.h

@@ -2,6 +2,8 @@
 #define JEMALLOC_INTERNAL_EXTERNS_H
 
 #include "jemalloc/internal/atomic.h"
+#include "jemalloc/internal/size_classes.h"
+#include "jemalloc/internal/tsd_types.h"
 
 /* TSD checks this to set thread local slow state accordingly. */
 extern bool	malloc_slow;