libcamera: Add todo comment in meson.build about switch to dependency('dl')

The dlopen() & co. functions are provided by libdl on some systems, and
but the C library on others. Starting from version 0.62.0, meson handles
this behind the scenes when using dependency('dl'). Add a todo comment
to remember we should replace the manual implementation with a
dependency() call when updating to meson 0.62.0 or newer.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>

src/libcamera/meson.build

@@ -69,6 +69,7 @@ subdir('proxy')
 
 null_dep = dependency('', required : false)
 
+# TODO: Use dependency('dl') when updating to meson 0.62.0 or newer.
 libdl = null_dep
 if not cc.has_function('dlopen')
     libdl = cc.find_library('dl')