vulncheck: don't define Binary in go1.18

Binary uses the debug/buildinfo package, which isn't introduced until
go1.18.

Change-Id: Ic724c12e6d8da649c325f9ed9ee87b2044a6a305
Reviewed-on: https://go-review.googlesource.com/c/vuln/+/395095
Trust: Julie Qiu <julie@golang.org>
Run-TryBot: Julie Qiu <julie@golang.org>
Reviewed-by: Jonathan Amsterdam <jba@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
diff --git a/vulncheck/binary.go b/vulncheck/binary.go
index b805c8a..cf04bee 100644
--- a/vulncheck/binary.go
+++ b/vulncheck/binary.go
@@ -2,6 +2,9 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build go1.18
+// +build go1.18
+
 package vulncheck
 
 import (
diff --git a/vulncheck/binary_test.go b/vulncheck/binary_test.go
index 63c090f..e7eb502 100644
--- a/vulncheck/binary_test.go
+++ b/vulncheck/binary_test.go
@@ -2,6 +2,9 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build go1.18
+// +build go1.18
+
 package vulncheck
 
 import (
diff --git a/vulncheck/internal/binscan/exe.go b/vulncheck/internal/binscan/exe.go
index 37399e1..fc2f862 100644
--- a/vulncheck/internal/binscan/exe.go
+++ b/vulncheck/internal/binscan/exe.go
@@ -2,6 +2,9 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build go1.18
+// +build go1.18
+
 package binscan
 
 // This file is a somewhat modified version of cmd/go/internal/version/exe.go
diff --git a/vulncheck/internal/binscan/scan.go b/vulncheck/internal/binscan/scan.go
index 35d0fcd..ec8a5ea 100644
--- a/vulncheck/internal/binscan/scan.go
+++ b/vulncheck/internal/binscan/scan.go
@@ -2,6 +2,9 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build go1.18
+// +build go1.18
+
 // Package binscan contains methods for parsing Go binary files for the purpose
 // of extracting module dependency and symbol table information.
 package binscan