storage: require cgo, not !plan9

I previously added !plan9 build tags to fix the build on plan9, but
this didn't fix other ports where sqlite3 wasn't available. What I
really wanted was to require cgo. This "fixes" the build for e.g.
linux/ppc64.

Change-Id: I2fd6e824f358ca0e3534458b3b8d900756de4bbe
Reviewed-on: https://go-review.googlesource.com/c/perf/+/174678
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
diff --git a/storage/app/query_test.go b/storage/app/query_test.go
index 8c228c7..56ef050 100644
--- a/storage/app/query_test.go
+++ b/storage/app/query_test.go
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build !plan9
+// +build cgo
 
 package app
 
diff --git a/storage/app/upload_test.go b/storage/app/upload_test.go
index 7260aa1..441cbc6 100644
--- a/storage/app/upload_test.go
+++ b/storage/app/upload_test.go
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build !plan9
+// +build cgo
 
 package app
 
diff --git a/storage/db/db_test.go b/storage/db/db_test.go
index bbc1d9d..1fa1987 100644
--- a/storage/db/db_test.go
+++ b/storage/db/db_test.go
@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+// +build cgo
+
 package db_test
 
 import (
diff --git a/storage/db/dbtest/dbtest.go b/storage/db/dbtest/dbtest.go
index 8fb0692..ce966ca 100644
--- a/storage/db/dbtest/dbtest.go
+++ b/storage/db/dbtest/dbtest.go
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build !plan9
+// +build cgo
 
 package dbtest
 
diff --git a/storage/db/sqlite3/sqlite3.go b/storage/db/sqlite3/sqlite3.go
index 6efb041..204053b 100644
--- a/storage/db/sqlite3/sqlite3.go
+++ b/storage/db/sqlite3/sqlite3.go
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build !plan9
+// +build cgo
 
 // Package sqlite3 provides the sqlite3 driver for
 // x/perf/storage/db. It must be imported instead of go-sqlite3 to
diff --git a/storage/localperfdata/app.go b/storage/localperfdata/app.go
index 8c34828..fc8eaea 100644
--- a/storage/localperfdata/app.go
+++ b/storage/localperfdata/app.go
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build !plan9
+// +build cgo
 
 // Localperfdata runs an HTTP server for benchmark storage.
 //