Clean up *PAGE* macros.

s/PAGE_SHIFT/LG_PAGE/g and s/PAGE_SIZE/PAGE/g.

Remove remnants of the dynamic-page-shift code.

Rename the "arenas.pagesize" mallctl to "arenas.page".

Remove the "arenas.chunksize" mallctl, which is redundant with
"opt.lg_chunk".

src/zone.c

@@ -78,7 +78,7 @@ zone_valloc(malloc_zone_t *zone, size_t size)
 {
 	void *ret = NULL; /* Assignment avoids useless compiler warning. */
 
-	je_posix_memalign(&ret, PAGE_SIZE, size);
+	je_posix_memalign(&ret, PAGE, size);
 
 	return (ret);
 }