[debugger] GTK_CHECK_VERSION points to unmaintained code

[WrapEarnPass]

As pointed out by @Skif-off in #1570

At least some of these checks are a legacy of the GTK2 -> GTK3 transition and of course will be removed in the future.

There are a lot of checks for GTK versions that geany no longer supports. These should be reviewed and refactored out if possible.

The utils checks seem like they may still be maintained, but are trending behind geany.
They should be reviewed as well.

./utils/src/gp_gtkcompat.h:#if GTK_CHECK_VERSION(3, 0, 0)
./utils/src/gp_gtkcompat.h:#if GTK_CHECK_VERSION(3, 10, 0)
./utils/src/gp_gtkcompat.h:#if GTK_CHECK_VERSION(3, 8, 0)
./debugger/src/dconfig.c:#if GTK_CHECK_VERSION(3, 0, 0)
./debugger/src/cell_renderers/cellrendererframeicon.c:#if GTK_CHECK_VERSION(3, 0, 0)
./debugger/src/cell_renderers/cellrendererframeicon.c:#if GTK_CHECK_VERSION(3, 0, 0)
./debugger/src/cell_renderers/cellrendererframeicon.c:#if GTK_CHECK_VERSION(3, 0, 0)
./debugger/src/cell_renderers/cellrendererframeicon.c:#if !GTK_CHECK_VERSION(3, 0, 0)
./debugger/src/cell_renderers/cellrendererframeicon.c:#if GTK_CHECK_VERSION(3, 0, 0)
./debugger/src/cell_renderers/cellrendererframeicon.c:#if !GTK_CHECK_VERSION(3, 0, 0)
./debugger/src/cell_renderers/cellrendererframeicon.c:#if !GTK_CHECK_VERSION(3, 0, 0)
./debugger/src/cell_renderers/cellrenderertoggle.c:#if GTK_CHECK_VERSION(3, 0, 0)
./debugger/src/cell_renderers/cellrendererbreakicon.c:#if GTK_CHECK_VERSION(3, 0, 0)
./debugger/src/cell_renderers/cellrendererbreakicon.c:#if GTK_CHECK_VERSION(3, 0, 0)
./debugger/src/cell_renderers/cellrendererbreakicon.c:#if !GTK_CHECK_VERSION(3, 0, 0)
./debugger/src/cell_renderers/cellrendererbreakicon.c:#if GTK_CHECK_VERSION(3, 0, 0)
./debugger/src/cell_renderers/cellrendererbreakicon.c:#if !GTK_CHECK_VERSION(3, 0, 0)
./debugger/src/cell_renderers/cellrendererbreakicon.c:#if !GTK_CHECK_VERSION(3, 0, 0)
./debugger/src/cell_renderers/cellrendererbreakicon.c:#if GTK_CHECK_VERSION(3, 0, 0)
./debugger/src/plugin.c:#if GTK_CHECK_VERSION(3, 0, 0)
./debugger/src/tpage.c:#if GTK_CHECK_VERSION(3, 0, 0)
./debugger/src/tpage.c:#if GTK_CHECK_VERSION(3, 0, 0)
./debugger/src/tpage.c:#if GTK_CHECK_VERSION(3, 0, 0)
./debugger/src/tpage.c:#if GTK_CHECK_VERSION(3, 0, 0)
./debugger/src/tpage.c:#if GTK_CHECK_VERSION(3, 0, 0)
./debugger/src/tpage.c:#if GTK_CHECK_VERSION(3, 0, 0)
./debugger/src/tpage.c:#if GTK_CHECK_VERSION(3, 0, 0)
./debugger/src/tpage.c:#if GTK_CHECK_VERSION(3, 0, 0)
./debugger/src/tpage.c:#if GTK_CHECK_VERSION(3, 0, 0)
./debugger/src/tpage.c:#if GTK_CHECK_VERSION(3, 0, 0)
./debugger/src/tpage.c:#if GTK_CHECK_VERSION(3, 0, 0)
./debugger/src/tpage.c:#if GTK_CHECK_VERSION(3, 0, 0)
./debugger/src/debug.c:#if GTK_CHECK_VERSION(3, 0, 0)
./debugger/src/debug.c:#if GTK_CHECK_VERSION(3, 0, 0)
./debugger/src/debug.c:#if GTK_CHECK_VERSION(3, 0, 0)
./debugger/src/debug.c:#if GTK_CHECK_VERSION(3, 0, 0)
./debugger/src/btnpanel.c:#if GTK_CHECK_VERSION(3, 0, 0)
./debugger/src/btnpanel.c:#if GTK_CHECK_VERSION(3, 0, 0)
./debugger/src/btnpanel.c:#if GTK_CHECK_VERSION(3, 0, 0)
./debugger/src/btnpanel.c:#if GTK_CHECK_VERSION(3, 0, 0)
./debugger/src/btnpanel.c:#if GTK_CHECK_VERSION(3, 0, 0)
./debugger/src/gui.c:#if GTK_CHECK_VERSION(3, 0, 0)