cmd/gomobile: rename bundleId to bundleID

Renames the argument to the -bundleid command line flag to be
consistent with other parameter naming.

Change-Id: Icde0be0fbacb08712c415abce462070a84aa46d9
Reviewed-on: https://go-review.googlesource.com/79115
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

cmd/gomobile/build.go

@@ -24,7 +24,7 @@ var tmpdir string
 var cmdBuild = &command{
 	run:   runBuild,
 	Name:  "build",
-	Usage: "[-target android|ios] [-o output] [-bundleid bundleId] [build flags] [package]",
+	Usage: "[-target android|ios] [-o output] [-bundleid bundleID] [build flags] [package]",
 	Short: "compile android APK and iOS app",
 	Long: `
 Build compiles and encodes the app named by the import path.