runtime: remove unused maxSliceCap function and maxElems array

All uses of these have been converted to use runtime/internal/math
functions for overflow checking.

Fixes #21588

Change-Id: I0ba57028e471803dc7d445e66d77a8f87edfdafb
Reviewed-on: https://go-review.googlesource.com/c/144037
Run-TryBot: Martin Möhrmann <martisch@uos.de>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>

src/cmd/compile/internal/gc/inl_test.go

@@ -54,7 +54,6 @@ func TestIntendedInlining(t *testing.T) {
 			"getm",
 			"isDirectIface",
 			"itabHashFunc",
-			"maxSliceCap",
 			"noescape",
 			"readUnaligned32",
 			"readUnaligned64",

src/runtime/slice.go

@@ -23,28 +23,6 @@ type notInHeapSlice struct {
 	cap   int
 }
 
-// maxElems is a lookup table containing the maximum capacity for a slice.
-// The index is the size of the slice element.
-var maxElems = [...]uintptr{
-	^uintptr(0),
-	maxAlloc / 1, maxAlloc / 2, maxAlloc / 3, maxAlloc / 4,
-	maxAlloc / 5, maxAlloc / 6, maxAlloc / 7, maxAlloc / 8,
-	maxAlloc / 9, maxAlloc / 10, maxAlloc / 11, maxAlloc / 12,
-	maxAlloc / 13, maxAlloc / 14, maxAlloc / 15, maxAlloc / 16,
-	maxAlloc / 17, maxAlloc / 18, maxAlloc / 19, maxAlloc / 20,
-	maxAlloc / 21, maxAlloc / 22, maxAlloc / 23, maxAlloc / 24,
-	maxAlloc / 25, maxAlloc / 26, maxAlloc / 27, maxAlloc / 28,
-	maxAlloc / 29, maxAlloc / 30, maxAlloc / 31, maxAlloc / 32,
-}
-
-// maxSliceCap returns the maximum capacity for a slice.
-func maxSliceCap(elemsize uintptr) uintptr {
-	if elemsize < uintptr(len(maxElems)) {
-		return maxElems[elemsize]
-	}
-	return maxAlloc / elemsize
-}
-
 func panicmakeslicelen() {
 	panic(errorString("makeslice: len out of range"))
 }