glsl/glcpp: move macro declaration before code to fix MSVC build

Reviewed-by: Carl Worth <cworth@cworth.org>
softpipe: fix sp_get_dims() for PIPE_BUFFER

Before, we were checking the level against view->u.tex.last_level but
level is not valid for buffers.  Plus, the aliasing of the view->u.tex
view->u.buf members (a union) caused the level checking arithmetic to
be totally wrong.  The net effect is we always returned early for
PIPE_BUFFER size queries.

This fixes the piglit "textureSize 140 fs samplerBuffer" test.

Reviewed-by: Roland Scheidegger <sroland@vmware.com>
gallium/docs: minor clarification for TXQ instruction

Reviewed-by: Ilia Mirkin <imirkin@alum.mit.edu>