Debugger: Use an aspect for the source path mapping

More in line with the other settings.

Change-Id: I86494f1955120cddda7d2f2eec8ba0fdbfd99585
Reviewed-by: David Schulz <david.schulz@qt.io>

src/plugins/debugger/debuggercore.h

@@ -42,8 +42,6 @@ namespace Utils { class BaseTreeView; }
 namespace Debugger {
 namespace Internal {
 
-class GlobalDebuggerOptions;
-
 enum TestCases
 {
     // Gdb
@@ -53,8 +51,6 @@ enum TestCases
 // Some convenience.
 void openTextEditor(const QString &titlePattern, const QString &contents);
 
-GlobalDebuggerOptions *globalDebuggerOptions();
-
 bool isTestRun();
 
 QAction *addAction(QMenu *menu, const QString &display, bool on,