replace some basic uses of fmt.Sprintf()

Really tiny gains here, and doesn't significantly impact readability:

    BenchmarkSprintf
    BenchmarkSprintf-10    11528700     91.59 ns/op   32 B/op  1 allocs/op
    BenchmarkConcat
    BenchmarkConcat-10    100000000     11.76 ns/op    0 B/op  0 allocs/op

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

cli/command/config/formatter.go

@@ -103,7 +103,7 @@ func (c *configContext) Labels() string {
 	}
 	var joinLabels []string
 	for k, v := range mapLabels {
-		joinLabels = append(joinLabels, fmt.Sprintf("%s=%s", k, v))
+		joinLabels = append(joinLabels, k+"="+v)
 	}
 	return strings.Join(joinLabels, ",")
 }

cli/command/container/create.go

@@ -91,7 +91,7 @@ func runCreate(dockerCli command.Cli, flags *pflag.FlagSet, options *createOptio
 		if v == nil {
 			newEnv = append(newEnv, k)
 		} else {
-			newEnv = append(newEnv, fmt.Sprintf("%s=%s", k, *v))
+			newEnv = append(newEnv, k+"="+*v)
 		}
 	}
 	copts.env = *opts.NewListOptsRef(&newEnv, nil)

cli/command/container/run.go

@@ -101,7 +101,7 @@ func runRun(dockerCli command.Cli, flags *pflag.FlagSet, ropts *runOptions, copt
 		if v == nil {
 			newEnv = append(newEnv, k)
 		} else {
-			newEnv = append(newEnv, fmt.Sprintf("%s=%s", k, *v))
+			newEnv = append(newEnv, k+"="+*v)
 		}
 	}
 	copts.env = *opts.NewListOptsRef(&newEnv, nil)

cli/command/formatter/container.go

@@ -247,7 +247,7 @@ func (c *ContainerContext) Labels() string {
 
 	var joinLabels []string
 	for k, v := range c.c.Labels {
-		joinLabels = append(joinLabels, fmt.Sprintf("%s=%s", k, v))
+		joinLabels = append(joinLabels, k+"="+v)
 	}
 	return strings.Join(joinLabels, ",")
 }

cli/command/network/formatter.go

@@ -103,7 +103,7 @@ func (c *networkContext) Labels() string {
 
 	var joinLabels []string
 	for k, v := range c.n.Labels {
-		joinLabels = append(joinLabels, fmt.Sprintf("%s=%s", k, v))
+		joinLabels = append(joinLabels, k+"="+v)
 	}
 	return strings.Join(joinLabels, ",")
 }

cli/command/secret/formatter.go

@@ -110,7 +110,7 @@ func (c *secretContext) Labels() string {
 	}
 	var joinLabels []string
 	for k, v := range mapLabels {
-		joinLabels = append(joinLabels, fmt.Sprintf("%s=%s", k, v))
+		joinLabels = append(joinLabels, k+"="+v)
 	}
 	return strings.Join(joinLabels, ",")
 }

cli/command/system/events.go

@@ -133,7 +133,7 @@ func prettyPrintEvent(out io.Writer, event eventtypes.Message) error {
 		sort.Strings(keys)
 		for _, k := range keys {
 			v := event.Actor.Attributes[k]
-			attrs = append(attrs, fmt.Sprintf("%s=%s", k, v))
+			attrs = append(attrs, k+"="+v)
 		}
 		fmt.Fprintf(out, " (%s)", strings.Join(attrs, ", "))
 	}

cli/compose/convert/service.go

@@ -1,7 +1,6 @@
 package convert
 
 import (
-	"fmt"
 	"os"
 	"sort"
 	"strings"
@@ -605,7 +604,7 @@ func convertEnvironment(source map[string]*string) []string {
 		case nil:
 			output = append(output, name)
 		default:
-			output = append(output, fmt.Sprintf("%s=%s", name, *value))
+			output = append(output, name+"="+*value)
 		}
 	}