GrFP can express distance vector field req., program builder declares variable for it

src/gpu/vk/GrVkProgramDesc.cpp

Index: src/gpu/vk/GrVkProgramDesc.cpp
diff --git a/src/gpu/vk/GrVkProgramDesc.cpp b/src/gpu/vk/GrVkProgramDesc.cpp
index 2154af652c7e7de3bc80854ee59b37ad9e999770..0e424e22e17ea2c22e6865cd2d02f17453f76c2e 100644
--- a/src/gpu/vk/GrVkProgramDesc.cpp
+++ b/src/gpu/vk/GrVkProgramDesc.cpp
@@ -160,6 +160,12 @@ bool GrVkProgramDescBuilder::Build(GrProgramDesc* desc,
         header->fIgnoresCoverage = 0;
     }
 
+    if (pipeline.usesDistanceVectorField()) {
+        header->fUsesDistanceVectorField = 1;
+    } else {
+        header->fUsesDistanceVectorField = 0;
+    }
+
     header->fSnapVerticesToPixelCenters = pipeline.snapVerticesToPixelCenters();
     header->fColorEffectCnt = pipeline.numColorFragmentProcessors();
     header->fCoverageEffectCnt = pipeline.numCoverageFragmentProcessors();