vulndb/govulncheck: use log instead of fmt for verbose mode

log provides timestamps, which are valuable for figuring out how long
things are actually taking.

Change-Id: I12820feda059b44e823524c5ecc9d394d3635dcf
Reviewed-on: https://go-review.googlesource.com/c/exp/+/333650
Trust: Roland Shoemaker <roland@golang.org>
Trust: Zvonimir Pavlinovic <zpavlinovic@google.com>
Run-TryBot: Roland Shoemaker <roland@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Zvonimir Pavlinovic <zpavlinovic@google.com>
diff --git a/vulndb/govulncheck/main.go b/vulndb/govulncheck/main.go
index ec38f44..7232c28 100644
--- a/vulndb/govulncheck/main.go
+++ b/vulndb/govulncheck/main.go
@@ -20,6 +20,7 @@
 	"flag"
 	"fmt"
 	"io"
+	"log"
 	"os"
 	"runtime"
 	"sort"
@@ -167,7 +168,7 @@
 
 	// Load packages.
 	if *verboseFlag {
-		fmt.Println("loading packages...")
+		log.Println("loading packages...")
 	}
 	pkgs, err := packages.Load(cfg, patterns...)
 	if err != nil {
@@ -177,12 +178,12 @@
 		return nil, fmt.Errorf("packages contain errors")
 	}
 	if *verboseFlag {
-		fmt.Printf("\t%d loaded packages\n", len(pkgs))
+		log.Printf("\t%d loaded packages\n", len(pkgs))
 	}
 
 	// Load database.
 	if *verboseFlag {
-		fmt.Println("loading database...")
+		log.Println("loading database...")
 	}
 	vulns, err := audit.LoadVulnerabilities(dbs, allPkgPaths(pkgs))
 	if err != nil {
@@ -190,7 +191,7 @@
 	}
 
 	if *verboseFlag {
-		fmt.Printf("\t%d known vulnerabilities.\n", len(vulns))
+		log.Printf("\t%d known vulnerabilities.\n", len(vulns))
 	}
 
 	// Load package versions.
@@ -198,17 +199,17 @@
 
 	// Load SSA.
 	if *verboseFlag {
-		fmt.Println("building ssa...")
+		log.Println("building ssa...")
 	}
 	prog, ssaPkgs := ssautil.AllPackages(pkgs, 0)
 	prog.Build()
 	if *verboseFlag {
-		fmt.Println("\tbuilt ssa.")
+		log.Println("\tbuilt ssa")
 	}
 
 	// Compute the findings.
 	if *verboseFlag {
-		fmt.Println("detecting vulnerabilities...")
+		log.Println("detecting vulnerabilities...")
 	}
 	var findings []audit.Finding
 	env := audit.Env{OS: runtime.GOOS, Arch: runtime.GOARCH, PkgVersions: pkgVersions, Vulns: vulns}
@@ -218,7 +219,7 @@
 		findings = audit.VulnerableSymbols(ssaPkgs, env)
 	}
 	if *verboseFlag {
-		fmt.Printf("\t%d detected findings.\n", len(findings))
+		log.Printf("\t%d detected findings.\n", len(findings))
 	}
 	return findings, nil
 }