render/gles2: use .x/.y instead of .s/.t
render/gles2: use .x/.y instead of .s/.t

texcoord is a vector of coordinates, with the first member being the X
axis value and the second member being the Y axis value. It makes more
sense to use the accessors with the same names.

ascent12/wlroots,ascent12/wlroots,SirCmpwn/wlroots,swaywm/wlroots,swaywm/wlroots