devel/dconf: Unbreak tests by fixing the check for the -Wl,--version-script flag

The Meson cc.get_supported_link_arguments() call boils down to

cc test.c ... -Wl,--version-script,/path/to/symbols.map

which fails with

ld: error: version script assignment of 'global' to symbol 'g_io_module_load' failed: symbol not defined

The error feels natural to me since test.c does not indeed define these symbols.
I have no idea how this check works on Linux.