st/xlib: Don't destroy screen on XCloseDisplay()
st/xlib: Don't destroy screen on XCloseDisplay()

screen may still be used by other resources that are not yet freed.
To correctly fix this there will be a need to account for resources
differently, but this quick fix is not any worse than the original
code that leaked screens anyway.

Reviewed-by: Brian Paul <3cb4e1df5ec4da2c7c4af7c52cec8cf340a55a10@vmware.com>

metora/MesaGLSLCompiler,metora/MesaGLSLCompiler,metora/MesaGLSLCompiler