Eevee: optimize vertex shader for probe and shadows.

source/blender/draw/engines/eevee/shaders/probe_geom.glsl

@@ -5,7 +5,7 @@ layout(triangle_strip, max_vertices=3) out;
 uniform int Layer;
 
 in vec4 vPos[];
-in int face[];
+flat in int face[];
 
 out vec3 worldPosition;
 out vec3 worldNormal; /* Required. otherwise generate linking error on AMD. */

source/blender/draw/engines/eevee/shaders/probe_vert.glsl

@@ -2,7 +2,7 @@
 in vec3 pos;
 
 out vec4 vPos;
-out int face;
+flat out int face;
 
 void main() {
 	vPos = vec4(pos, 1.0);

source/blender/draw/engines/eevee/shaders/shadow_geom.glsl

@@ -8,7 +8,7 @@ layout(std140) uniform shadow_render_block {
 };
 
 in vec4 vPos[];
-in int face[];
+flat in int face[];
 
 void main() {
 	int f = face[0];

source/blender/draw/engines/eevee/shaders/shadow_vert.glsl

@@ -4,7 +4,7 @@ uniform mat4 ShadowModelMatrix;
 in vec3 pos;
 
 out vec4 vPos;
-out int face;
+flat out int face;
 
 void main() {
 	vPos = ShadowModelMatrix * vec4(pos, 1.0);