glx: Call __glXInitVertexArrayState() with a usable gc.

glx: Call __glXInitVertexArrayState() with a usable gc.

For each indirect context the indirect vertex array state must be initialised
by __glXInitVertexArrayState in indirect_vertex_array.c.  As noted in the
routine header it requires that the glx context has been setup prior to the
call, in order to test the server version and extensions.

Currently __glXInitVertexArrayState is called from indirect_bind_context in
indirect_glx.c, as follows:

   state = gc->client_state_private;
   if (state->array_state == NULL) {
      glGetString(GL_EXTENSIONS);
      glGetString(GL_VERSION);
      __glXInitVertexArrayState(gc);
   }

But, the gc context is not yet usable at this stage, so the server queries
fail, and __glXInitVertexArrayState is called without the server version and
extension information it needs.  This breaks multi-texturing as
glXInitVertexArrayState doesn't get GL_MAX_TEXTURE_UNITS.  It probably also
breaks setup of other arrays: fog, secondary colour, vertex attributes.

To fix this I have moved the call to __glXInitVertexArrayState to the end of
MakeContextCurrent in glxcurrent.c, where the glx context is usable.

Fixes a regression caused by commit 4fbdde889c. Fixes ARB_vertex_program
usage in the arbvparray Mesa demo when run with indirect GLX and also
the tex-skipped-unit piglit test when run with indirect GLX.

Reviewed-by: Matt Turner <mattst88@gmail.com>
Acked-by: Ian Romanick <ian.d.romanick@intel.com>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=61907