remove kA1_Config, as it is no longer supported

tests/ImageDecodingTest.cpp

Index: tests/ImageDecodingTest.cpp
diff --git a/tests/ImageDecodingTest.cpp b/tests/ImageDecodingTest.cpp
index 56193f4e470a8b0301c821331210caa59dace632..6fcef1d31543ba782f2a77653e64a3a0e2b2bb8e 100644
--- a/tests/ImageDecodingTest.cpp
+++ b/tests/ImageDecodingTest.cpp
@@ -148,7 +148,7 @@ public:
         // the list is that each one is different, so we can test
         // to make sure the correct config is chosen.
         const SkBitmap::Config configs[] = {
-            SkBitmap::kA1_Config,
+            SkBitmap::kA8_Config,
             SkBitmap::kA8_Config,
             SkBitmap::kIndex8_Config,
             SkBitmap::kRGB_565_Config,