spirv: Enable double floating points when copying variables in _vtn_variable_copy()
spirv: Enable double floating points when copying variables in _vtn_variable_copy()

Signed-off-by: Samuel Iglesias Gonsálvez <b753b212f30aed827c3eea2e437609dc37310153@igalia.com>
Reviewed-by: Jason Ekstrand <68c46a606457643eab92053c1c05574abb26f861@jlekstrand.net>

metora/MesaGLSLCompiler,metora/MesaGLSLCompiler,metora/MesaGLSLCompiler