Let "archiving core" message appear only if verbose

Fixes arduino#238

Author: facchinm

Diff for: src/arduino.cc/builder/constants/constants.go

@@ -150,6 +150,7 @@ const LOG_LEVEL_ERROR = "error"
 const LOG_LEVEL_INFO = "info"
 const LOG_LEVEL_WARN = "warn"
 const MSG_ARCH_FOLDER_NOT_SUPPORTED = "'arch' folder is no longer supported! See http://goo.gl/gfFJzU for more information"
+const MSG_ARCHIVING_CORE_CACHE = "Archiving built core (caching) in: {0}"
 const MSG_BOARD_UNKNOWN = "Board {0} (platform {1}, package {2}) is unknown"
 const MSG_BOOTLOADER_FILE_MISSING = "Bootloader file specified but missing: {0}"
 const MSG_BUILD_OPTIONS_CHANGED = "Build options changed, rebuilding all"

Diff for: src/arduino.cc/builder/phases/core_builder.go

@@ -30,6 +30,7 @@
 package phases
 
 import (
+	"os"
 	"path/filepath"
 
 	"arduino.cc/builder/builder_utils"
@@ -126,7 +127,9 @@ func compileCore(buildPath string, buildCachePath string, buildProperties proper
 
 	// archive core.a
 	if targetArchivedCore != "" {
-		logger.Println(constants.LOG_LEVEL_DEBUG, "Archiving built core (caching) in: "+targetArchivedCore)
+		if verbose {
+			logger.Fprintln(os.Stdout, constants.LOG_LEVEL_DEBUG, constants.MSG_ARCHIVING_CORE_CACHE, targetArchivedCore)
+		}
 		builder_utils.CopyFile(archiveFile, targetArchivedCore)
 	}