cmake-gui: Rename local variable to avoid shadowing a member

Address warnings:

 Source/QtDialog/CMakeSetupDialog.cxx:1233:15:
 warning: declaration of 'cursor' shadows a member of 'this' [-Wshadow]
 Source/QtDialog/CMakeSetupDialog.cxx:1260:15:
 warning: declaration of 'cursor' shadows a member of 'this' [-Wshadow]

by renaming the local variable to 'textCursor'.
Merge topic 'cmake-gui-warning' into next

82bacea cmake-gui: Rename local variable to avoid shadowing a member