SkPath: Cleanup code to make array size match

This has no functional change.

We change the declaration of our function argument to have an array
size which matches the incoming argument.  Since C++ treats this
argument as just a function pointer regardless of the declared size,
there's no functional change.  But it makes the code clearer and
prevents static analysis tools from flagging a possible out-of-bound
access.

Change-Id: I896a74d90e56d993887ef38e389b6e9535b47925
Reviewed-on: https://skia-review.googlesource.com/c/191062
Reviewed-by: Mike Klein <mtklein@google.com>
Commit-Queue: Mike Klein <mtklein@google.com>
diff --git a/src/core/SkPath.cpp b/src/core/SkPath.cpp
index 9650849..9f87e5a 100644
--- a/src/core/SkPath.cpp
+++ b/src/core/SkPath.cpp
@@ -3865,7 +3865,7 @@
     return n + 1;
 }
 
-static int compute_cubic_extremas(const SkPoint src[3], SkPoint extremas[5]) {
+static int compute_cubic_extremas(const SkPoint src[4], SkPoint extremas[5]) {
     SkScalar ts[4];
     int n  = SkFindCubicExtrema(src[0].fX, src[1].fX, src[2].fX, src[3].fX, ts);
         n += SkFindCubicExtrema(src[0].fY, src[1].fY, src[2].fY, src[3].fY, &ts[n]);