internal/memory: skip TestRead on non-linux platforms

Don't assume that /proc/meminfo exists on non-Linux platforms.

For #61209

Change-Id: I77cd968004f6f7cacb20b926a3cf8fc60e2c9525
Reviewed-on: https://go-review.googlesource.com/c/pkgsite/+/508296
Run-TryBot: Michael Matloob <matloob@google.com>
Reviewed-by: Robert Findley <rfindley@google.com>
TryBot-Bypass: Michael Matloob <matloob@google.com>

internal/memory/memory_test.go

@@ -10,8 +10,8 @@ import (
 )
 
 func TestRead(t *testing.T) {
-	if runtime.GOOS == "darwin" {
-		t.Skip("darwin has no /proc/meminfo")
+	if runtime.GOOS != "linux" {
+		t.Skip("don't assume /proc/meminfo exists on non-linux platforms")
 	}
 	_, err := ReadSystemStats()
 	if err != nil {