Fix tests for ExprHasNoEffect on non-Linux systems.

Author: Max Schaefer

ql/test/query-tests/RedundantCode/ExprHasNoEffect/tst_nonlinux.go

@@ -0,0 +1,7 @@
+// +build !linux
+
+package main
+
+func dostuff() {
+	panic("non-linux")
+}