Don't enable multisampling

It never worked in the first place, because we were
never requesting it in glutin, and it provides no value
given that textures are already antialiased.

alacritty/src/renderer/text/glsl3.rs

@@ -50,7 +50,6 @@ impl Glsl3Renderer {
         unsafe {
             gl::Enable(gl::BLEND);
             gl::BlendFunc(gl::SRC1_COLOR, gl::ONE_MINUS_SRC1_COLOR);
-            gl::Enable(gl::MULTISAMPLE);
 
             // Disable depth mask, as the renderer never uses depth tests.
             gl::DepthMask(gl::FALSE);