Git: Factor out resolving of bin directory on Windows

Change-Id: Ifbafa0f5cb8329faedfd1da3674b87e46001acc3
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@digia.com>
Reviewed-by: Tobias Hunger <tobias.hunger@digia.com>

src/plugins/git/gerrit/gerritplugin.cpp

@@ -399,6 +399,11 @@ QString GerritPlugin::gitBinary()
     return git;
 }
 
+Utils::FileName GerritPlugin::gitBinDirectory()
+{
+    return gitClient()->gitBinDirectory();
+}
+
 // Find the branch of a repository.
 QString GerritPlugin::branch(const QString &repository)
 {