Git/VCS: Use spinning progress indicator for log view

Show a spinning progress indicator instead of the "Waiting for data"
text for e.g. the git log view and other commands that use
VcsBaseEditor.

Change-Id: Ie4c73f85397f8809bda6bb276140eb695d96174f
Reviewed-by: Orgad Shaneh <orgads@gmail.com>

src/plugins/git/gitclient.h

@@ -435,7 +435,6 @@ private:
     mutable Utils::FileName m_gitVersionForBinary;
     mutable unsigned m_cachedGitVersion;
 
-    const QString m_msgWait;
     GitSettings *m_settings;
     QString m_gitQtcEditor;
     QMap<QString, StashInfo> m_stashInfo;