runtime: remove useless constant definition in malloc.go

Change-Id: I060c867d89a06b5a44fbe77804c19299385802d9
Reviewed-on: https://go-review.googlesource.com/c/go/+/311250
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Run-TryBot: Dmitri Shuralyov <dmitshur@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
Reviewed-by: Keith Randall <khr@google.com>
Auto-Submit: Dmitri Shuralyov <dmitshur@golang.org>

src/runtime/malloc.go

diff --git a/src/runtime/malloc.go b/src/runtime/malloc.go
index 14bf9a5..eb24fdb 100644
--- a/src/runtime/malloc.go
+++ b/src/runtime/malloc.go
@@ -110,18 +110,12 @@
 )
 
 const (
-	debugMalloc = false
-
 	maxTinySize   = _TinySize
 	tinySizeClass = _TinySizeClass
 	maxSmallSize  = _MaxSmallSize
 
 	pageShift = _PageShift
 	pageSize  = _PageSize
-	pageMask  = _PageMask
-	// By construction, single page spans of the smallest object class
-	// have the most objects per span.
-	maxObjsPerSpan = pageSize / 8
 
 	concurrentSweep = _ConcurrentSweep