Fix UB function problems for AA merger.

src/core/SkAAClip.cpp

Index: src/core/SkAAClip.cpp
diff --git a/src/core/SkAAClip.cpp b/src/core/SkAAClip.cpp
index bbd1f555f08d49f1e6d11f346c1dfb93934d771e..0de6d350eb17c390b318b0073177013f026fb1e8 100644
--- a/src/core/SkAAClip.cpp
+++ b/src/core/SkAAClip.cpp
@@ -2056,9 +2056,10 @@ static inline uint16_t mergeOne(uint16_t value, unsigned alpha) {
                        SkMulDiv255Round(b, alpha));
 }
 
-template <typename T> void mergeT(const T* SK_RESTRICT src, int srcN,
-                                 const uint8_t* SK_RESTRICT row, int rowN,
-                                 T* SK_RESTRICT dst) {
+template <typename T>
+void mergeT(const void* inSrc, int srcN, const uint8_t* SK_RESTRICT row, int rowN, void* inDst) {
+    const T* SK_RESTRICT src = static_cast<const T*>(inSrc);
+    T* SK_RESTRICT       dst = static_cast<T*>(inDst);
     for (;;) {
         SkASSERT(rowN > 0);
         SkASSERT(srcN > 0);
@@ -2094,14 +2095,10 @@ static MergeAAProc find_merge_aa_proc(SkMask::Format format) {
             SkDEBUGFAIL("unsupported");
             return nullptr;
         case SkMask::kA8_Format:
-        case SkMask::k3D_Format: {
-            void (*proc8)(const uint8_t*, int, const uint8_t*, int, uint8_t*) = mergeT;
-            return (MergeAAProc)proc8;
-        }
-        case SkMask::kLCD16_Format: {
-            void (*proc16)(const uint16_t*, int, const uint8_t*, int, uint16_t*) = mergeT;
-            return (MergeAAProc)proc16;
-        }
+        case SkMask::k3D_Format:
+            return mergeT<uint8_t> ;
+        case SkMask::kLCD16_Format:
+            return mergeT<uint16_t>;
         default:
             SkDEBUGFAIL("unsupported");
             return nullptr;