Text: don't reuse the same pixel values in this test either.

Should have done it in aeedd681b2 for both
GlyphCacheGL and DistanceFieldGlyphCacheGL, not sure why I didn't.

src/Magnum/Text/Test/DistanceFieldGlyphCacheGLTest.cpp

@@ -319,8 +319,8 @@ void DistanceFieldGlyphCacheGLTest::setProcessedImage() {
     UnsignedByte imageData[]{
         0x00, 0x11, 0x22, 0x33, 0x44, 0x55, 0x66, 0x77,
         0x88, 0x99, 0xaa, 0xbb, 0xcc, 0xdd, 0xee, 0xff,
-        0x00, 0x11, 0x22, 0x33, 0x44, 0x55, 0x66, 0x77,
-        0x88, 0x99, 0xaa, 0xbb, 0xcc, 0xdd, 0xee, 0xff,
+        0x00, 0xff, 0x11, 0xee, 0x22, 0xdd, 0x33, 0xcc,
+        0x44, 0xbb, 0x55, 0xaa, 0x66, 0x99, 0x77, 0x88,
     };
 
     #ifdef MAGNUM_BUILD_DEPRECATED
@@ -375,8 +375,8 @@ void DistanceFieldGlyphCacheGLTest::setProcessedImage() {
         0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
         0, 0, 0, 0, 0, 0, 0, 0, 0x00, 0x11, 0x22, 0x33, 0x44, 0x55, 0x66, 0x77,
         0, 0, 0, 0, 0, 0, 0, 0, 0x88, 0x99, 0xaa, 0xbb, 0xcc, 0xdd, 0xee, 0xff,
-        0, 0, 0, 0, 0, 0, 0, 0, 0x00, 0x11, 0x22, 0x33, 0x44, 0x55, 0x66, 0x77,
-        0, 0, 0, 0, 0, 0, 0, 0, 0x88, 0x99, 0xaa, 0xbb, 0xcc, 0xdd, 0xee, 0xff,
+        0, 0, 0, 0, 0, 0, 0, 0, 0x00, 0xff, 0x11, 0xee, 0x22, 0xdd, 0x33, 0xcc,
+        0, 0, 0, 0, 0, 0, 0, 0, 0x44, 0xbb, 0x55, 0xaa, 0x66, 0x99, 0x77, 0x88,
     };
     CORRADE_COMPARE_AS(actual,
         (ImageView2D{PixelFormat::R8Unorm, {16, 8}, expected}),