meson.build: xxf86vm is not needed for -Dglx-direct=false
It is only used in src/glx/glxcmds.c and when GLX_DIRECT_RENDERING is defined. So only depend on it if GLX direct rendering is actually enabled.
It is only used in src/glx/glxcmds.c and when GLX_DIRECT_RENDERING is defined. So only depend on it if GLX direct rendering is actually enabled.