Fixing several validation related issues

data/shaders/glsl/multiview/multiview.vert

@@ -19,11 +19,6 @@ layout (binding = 0) uniform UBO
 	vec4 lightPos;
 } ubo;
 
-out gl_PerVertex
-{
-	vec4 gl_Position;
-};
-
 void main() 
 {
 	outColor = inColor;

data/shaders/glsl/multiview/viewdisplay.vert

@@ -2,11 +2,6 @@
 
 layout (location = 0) out vec2 outUV;
 
-out gl_PerVertex
-{
-	vec4 gl_Position;
-};
-
 void main() 
 {
 	outUV = vec2((gl_VertexIndex << 1) & 2, gl_VertexIndex & 2);