meson: Fix linking flag in pkgconfig for mingw

Open Biswapriyo Nath requested to merge Biswa96/gtk:meson-mingw-pkgconfig into gtk-3-24

This changes the extra libs in pkgconfig from -Wl,-luuid to -luuid. Because the uuid is a system library and not a linker flag. This also fixes the following error while using gtk3 in golang program. go build invalid flag in pkg-config --libs: -Wl,-luuid

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