Another memcpy -> sk_careful_memcpy

https://uberchromegw.corp.google.com/i/client.skia/builders/Test-Ubuntu-GCC-GCE-CPU-AVX2-x86_64-Debug-ASAN/builds/3787/steps/dm/logs/stdio

dst is null.
TBR=herb@google.com

BUG=skia:

Review URL: https://codereview.chromium.org/1507113007
diff --git a/src/core/SkPath.cpp b/src/core/SkPath.cpp
index 351629d..1572354 100644
--- a/src/core/SkPath.cpp
+++ b/src/core/SkPath.cpp
@@ -583,7 +583,7 @@
     SkASSERT(max >= 0);
     SkASSERT(!max || dst);
     int count = SkMin32(max, fPathRef->countPoints());
-    memcpy(dst, fPathRef->points(), count * sizeof(SkPoint));
+    sk_careful_memcpy(dst, fPathRef->points(), count * sizeof(SkPoint));
     return fPathRef->countPoints();
 }