2 pixel-aligned vertical lines shortcut

[guzba]

before:

[pixie] rect opaque ................ 0.042 ms      0.046 ms    ±0.004  x1000
[pixie] rect not opaque ............ 0.132 ms      0.134 ms    ±0.005  x1000
[pixie] roundedRect opaque ......... 0.082 ms      0.088 ms    ±0.006  x1000
[pixie] roundedRect not opaque ..... 0.242 ms      0.246 ms    ±0.011  x1000

after:

[pixie] rect opaque ................ 0.035 ms      0.037 ms    ±0.004  x1000 < tied now
[pixie] rect not opaque ............ 0.123 ms      0.127 ms    ±0.009  x1000 < even faster
[pixie] roundedRect opaque ......... 0.066 ms      0.069 ms    ±0.002  x1000 < getting better
[pixie] roundedRect not opaque ..... 0.235 ms      0.239 ms    ±0.011  x1000 < getting better

cairo:

[cairo] rect opaque ................ 0.035 ms      0.037 ms    ±0.004  x1000
[cairo] rect not opaque ............ 0.142 ms      0.145 ms    ±0.007  x1000
[cairo] roundedRect opaque ......... 0.053 ms      0.060 ms    ±0.009  x1000
[cairo] roundedRect not opaque ..... 0.192 ms      0.195 ms    ±0.006  x1000