meson: Export winsys function symbols for target va

Export winsys function symbols of target va, even if the user
links with '-Bsymbolic-functions'.

It refers target vdpau, which commit is:
8c136b53b7
("fix vdpau interop when using -Bsymbolic-functions in ldflags")

Signed-off-by: Feng Jiang <jiangfeng@kylinos.cn>
Reviewed-by: Marek Olšák <marek.olsak@amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/23177>

src/gallium/targets/va/meson.build

@@ -30,6 +30,10 @@ if with_ld_version_script
   va_link_args += ['-Wl,--version-script', join_paths(meson.current_source_dir(), 'va.sym')]
   va_link_depends += files('va.sym')
 endif
+if with_ld_dynamic_list
+  va_link_args += ['-Wl,--dynamic-list', join_paths(meson.current_source_dir(), '../dri-vdpau.dyn')]
+  va_link_depends += files('../dri-vdpau.dyn')
+endif
 
 link_with_libva_gallium = [
   libgalliumvlwinsys, libgalliumvl, libgallium,