Adds fixes for react-native-windows UWP (#848)

Summary:
Specifically, updates the UWP .vcxproj for MSBuild and also exposes the UseLegacyStretchBehaviour API for use with react-native-windows.
Pull Request resolved: facebook/yoga#848

Reviewed By: SidharthGuglani

Differential Revision: D13848609

Pulled By: davidaurelio

fbshipit-source-id: eab046ff3c47e49706f515e209d8aaf750c2198f

Author: rozele

ReactCommon/yoga/yoga/YGMacros.h

@@ -20,14 +20,6 @@
 #define WIN_EXPORT
 #endif
 
-#ifdef WINARMDLL
-#define WIN_STRUCT(type) type*
-#define WIN_STRUCT_REF(value) &value
-#else
-#define WIN_STRUCT(type) type
-#define WIN_STRUCT_REF(value) value
-#endif
-
 #ifdef NS_ENUM
 // Cannot use NSInteger as NSInteger has a different size than int (which is the
 // default type of a enum). Therefor when linking the Yoga C library into obj-c

ReactCommon/yoga/yoga/Yoga.cpp

@@ -602,12 +602,12 @@ inline detail::CompactValue Value::create<YGUnitAuto>(float) {
 template <YGStyle::Dimensions YGStyle::*P>
 struct DimensionProp {
   template <YGDimension idx>
-  static WIN_STRUCT(YGValue) get(YGNodeRef node) {
+  static YGValue get(YGNodeRef node) {
     YGValue value = (node->getStyle().*P)[idx];
     if (value.unit == YGUnitUndefined || value.unit == YGUnitAuto) {
       value.value = YGUndefined;
     }
-    return WIN_STRUCT_REF(value);
+    return value;
   }
 
   template <YGDimension idx, YGUnit U>
@@ -690,13 +690,12 @@ struct DimensionProp {
     }                                                                     \
   }                                                                       \
                                                                           \
-  WIN_STRUCT(type)                                                        \
-  YGNodeStyleGet##name(const YGNodeRef node, const YGEdge edge) {         \
+  type YGNodeStyleGet##name(const YGNodeRef node, const YGEdge edge) {    \
     YGValue value = node->getStyle().instanceName[edge];                  \
     if (value.unit == YGUnitUndefined || value.unit == YGUnitAuto) {      \
       value.value = YGUndefined;                                          \
     }                                                                     \
-    return WIN_STRUCT_REF(value);                                         \
+    return value;                                                         \
   }
 
 #define YG_NODE_LAYOUT_PROPERTY_IMPL(type, name, instanceName) \

ReactCommon/yoga/yoga/Yoga.h

@@ -140,11 +140,11 @@ YGDirtiedFunc YGNodeGetDirtiedFunc(YGNodeRef node);
 void YGNodeSetDirtiedFunc(YGNodeRef node, YGDirtiedFunc dirtiedFunc);
 YGPrintFunc YGNodeGetPrintFunc(YGNodeRef node);
 void YGNodeSetPrintFunc(YGNodeRef node, YGPrintFunc printFunc);
-bool YGNodeGetHasNewLayout(YGNodeRef node);
-void YGNodeSetHasNewLayout(YGNodeRef node, bool hasNewLayout);
+WIN_EXPORT bool YGNodeGetHasNewLayout(YGNodeRef node);
+WIN_EXPORT void YGNodeSetHasNewLayout(YGNodeRef node, bool hasNewLayout);
 YGNodeType YGNodeGetNodeType(YGNodeRef node);
 void YGNodeSetNodeType(YGNodeRef node, YGNodeType nodeType);
-bool YGNodeIsDirty(YGNodeRef node);
+WIN_EXPORT bool YGNodeIsDirty(YGNodeRef node);
 bool YGNodeLayoutGetDidUseLegacyFlag(const YGNodeRef node);
 
 WIN_EXPORT void YGNodeStyleSetDirection(
@@ -227,8 +227,8 @@ WIN_EXPORT void YGNodeStyleSetPositionPercent(
     const YGNodeRef node,
     const YGEdge edge,
     const float position);
-WIN_EXPORT WIN_STRUCT(YGValue)
-    YGNodeStyleGetPosition(const YGNodeRef node, const YGEdge edge);
+WIN_EXPORT YGValue
+YGNodeStyleGetPosition(const YGNodeRef node, const YGEdge edge);
 
 WIN_EXPORT void YGNodeStyleSetMargin(
     const YGNodeRef node,