CMake: fix find link at

Change-Id: I1afcd3bd2b4db53ff8284f9acbe2b07102e66205
Reviewed-by: Eike Ziller <eike.ziller@qt.io>
Reviewed-by: <github-actions-qt-creator@cristianadam.eu>

src/plugins/cmakeprojectmanager/cmakeeditor.cpp

@@ -157,7 +157,7 @@ void CMakeEditorWidget::findLinkAt(const QTextCursor &cursor,
 
     // find the beginning of a filename
     QString buffer;
-    int beginPos = column;
+    int beginPos = column - 1;
     while (beginPos >= 0) {
         if (isValidFileNameChar(block, beginPos)) {
             buffer.prepend(block.at(beginPos));