VCS[git]: Environment settings.

Make GitClient::synchronousGit use the process environment.

Windows: Add a setting to fake a 'HOME' environment variable
(%HOMEDRIVE%%HOMEPATH%) to make msysgit look for its SSH-keys
there not only when run from git bash, but also from Qt Creator.
Useful in MinGw-setups, where git must not be in the path.

src/plugins/git/gitclient.h

@@ -212,6 +212,7 @@ public:
 
     QStringList binary() const; // Executable + basic arguments
     QProcessEnvironment processEnvironment() const;
+    static QString fakeWinHome(const QProcessEnvironment &e);
 
     static QString msgNoChangedFiles();
 
@@ -279,7 +280,6 @@ private:
     bool          m_hasCachedGitVersion;
 };
 
-
 } // namespace Internal
 } // namespace Git