Bundle 3 branches on fast path into tsd_state.

Added tsd_state_nominal_slow, which on fast path malloc() incorporates
tcache_enabled check, and on fast path free() bundles both malloc_slow and
tcache_enabled branches.

include/jemalloc/internal/jemalloc_internal_externs.h

@@ -3,6 +3,10 @@
 
 #include "jemalloc/internal/atomic.h"
 
+/* TSD checks this to set thread local slow state accordingly. */
+extern bool	malloc_slow;
+
+/* Run-time options. */
 extern bool	opt_abort;
 extern const char	*opt_junk;
 extern bool	opt_junk_alloc;