fix builder winding again

Record the nesting level when finding the edge winding contribution
so that inner edges can be reversed as needed.

R=fmalita@chromium.org
BUG=skia:3838

Review URL: https://codereview.chromium.org/1140383002
diff --git a/src/pathops/SkPathOpsDebug.cpp b/src/pathops/SkPathOpsDebug.cpp
index d28dc72..627a7c9 100644
--- a/src/pathops/SkPathOpsDebug.cpp
+++ b/src/pathops/SkPathOpsDebug.cpp
@@ -547,7 +547,9 @@
 
 void SkOpPtT::debugValidate() const {
 #if DEBUG_VALIDATE
-    if (contour()->globalState()->phase() == SkOpGlobalState::kIntersecting) {
+    SkOpGlobalState::Phase phase = contour()->globalState()->phase();
+    if (phase == SkOpGlobalState::kIntersecting
+            || phase == SkOpGlobalState::kFixWinding) {
         return;
     }
     SkASSERT(fNext);