BuildConfiguration: Add static helper to turn buildtype into a string

Use that helper in the projectexplorer instead of hardcoding a mapping
there.

Change-Id: I8720607a869c086569661fc9e9326ed6e0f85bb3
Reviewed-by: Ulf Hermann <ulf.hermann@theqtcompany.com>

src/plugins/projectexplorer/buildconfiguration.cpp

@@ -306,6 +306,21 @@ QString BuildConfiguration::disabledReason() const
     return QString();
 }
 
+QString BuildConfiguration::buildTypeName(BuildConfiguration::BuildType type)
+{
+    switch (type) {
+    case ProjectExplorer::BuildConfiguration::Debug:
+        return QLatin1String("debug");
+    case ProjectExplorer::BuildConfiguration::Profile:
+        return QLatin1String("profile");
+    case ProjectExplorer::BuildConfiguration::Release:
+        return QLatin1String("release");
+    case ProjectExplorer::BuildConfiguration::Unknown: // fallthrough
+    default:
+        return QLatin1String("unknown");
+    }
+}
+
 ///
 // IBuildConfigurationFactory
 ///