build(glx): Fix build by adding missing deps
dri3_glx.c includes xshmfence and glxcmds.c includes xf86vm, neither of which are listed as dependencies of the glx lib in the meson.build file. Consequently, those files would fail to compile on machines that did not have xshmfence and xf86vm installed globally. This commit rectifies the issue by adding the missing dependencies