Shaders: clean up base array layer setting in Flat and Phong tests.

Do it always when Flag::TextureArrays is set, not inside handling of
some particular texture. Because that way it won't work when other
textures are added/tested.

src/Magnum/Shaders/Test/FlatGLTest.cpp

@@ -2615,8 +2615,6 @@ template<FlatGL2D::Flag flag> void FlatGLTest::renderInstanced2D() {
                 .setSubImage(0, {image->size().x()/2, 0, 3}, second)
                 .setSubImage(0, {0, 0, 4}, third);
             shader.bindTexture(textureArray);
-            if(flag != FlatGL2D::Flag::UniformBuffers)
-                shader.setTextureLayer(2); /* base offset */
 
         } else
         #endif
@@ -2647,6 +2645,11 @@ template<FlatGL2D::Flag flag> void FlatGLTest::renderInstanced2D() {
                 Vector2{0.5f}
             ));
 
+        #ifndef MAGNUM_TARGET_GLES2
+        if(data.flags & FlatGL2D::Flag::TextureArrays)
+            shader.setTextureLayer(2); /* base offset */
+        #endif
+
         #ifndef MAGNUM_TARGET_GLES2
         if(data.flags & FlatGL2D::Flag::ObjectId) {
             /* Gets added to the per-instance ID, if that's enabled as well */
@@ -2879,8 +2882,6 @@ template<FlatGL3D::Flag flag> void FlatGLTest::renderInstanced3D() {
                 .setSubImage(0, {image->size().x()/2, 0, 3}, second)
                 .setSubImage(0, {0, 0, 4}, third);
             shader.bindTexture(textureArray);
-            if(flag != FlatGL2D::Flag::UniformBuffers)
-                shader.setTextureLayer(2); /* base offset */
 
         } else
         #endif
@@ -2912,6 +2913,11 @@ template<FlatGL3D::Flag flag> void FlatGLTest::renderInstanced3D() {
                 Vector2{0.5f}
             ));
 
+        #ifndef MAGNUM_TARGET_GLES2
+        if(data.flags & FlatGL3D::Flag::TextureArrays)
+            shader.setTextureLayer(2); /* base offset */
+        #endif
+
         #ifndef MAGNUM_TARGET_GLES2
         if(data.flags & FlatGL3D::Flag::ObjectId) {
             /* Gets added to the per-instance ID, if that's enabled as well */

src/Magnum/Shaders/Test/PhongGLTest.cpp

@@ -3518,8 +3518,6 @@ template<PhongGL::Flag flag> void PhongGLTest::renderInstanced() {
                     .setSubImage(0, {image->size().x()/2, 0, 3}, second)
                     .setSubImage(0, {0, 0, 4}, third);
                 shader.bindDiffuseTexture(diffuseArray);
-                if(flag != PhongGL::Flag::UniformBuffers)
-                    shader.setTextureLayer(2); /* base offset */
 
             } else
             #endif
@@ -3616,7 +3614,7 @@ template<PhongGL::Flag flag> void PhongGLTest::renderInstanced() {
                 Vector2{0.5f}
             ));
         #ifndef MAGNUM_TARGET_GLES2
-        if((data.flags & PhongGL::Flag::TextureArrays) && flag != PhongGL::Flag::UniformBuffers)
+        if(data.flags & PhongGL::Flag::TextureArrays)
             shader.setTextureLayer(2); /* base offset */
         #endif