Initialize variable to appease compiler warning

src/gpu/vk/GrVkPipelineStateBuilder.cpp

Index: src/gpu/vk/GrVkPipelineStateBuilder.cpp
diff --git a/src/gpu/vk/GrVkPipelineStateBuilder.cpp b/src/gpu/vk/GrVkPipelineStateBuilder.cpp
index 00e81d4b9ca91d7c31beecddb361deb0466b8481..6d46ea91b5f7545ef38c97f6aaf3bdfe347b0a75 100644
--- a/src/gpu/vk/GrVkPipelineStateBuilder.cpp
+++ b/src/gpu/vk/GrVkPipelineStateBuilder.cpp
@@ -99,7 +99,7 @@ bool GrVkPipelineStateBuilder::CreateVkShaderModule(const GrVkGpu* gpu,
     moduleCreateInfo.pNext = nullptr;
     moduleCreateInfo.flags = 0;
 
-    shaderc_compilation_result_t result;
+    shaderc_compilation_result_t result = nullptr;
 
     if (gpu->vkCaps().canUseGLSLForShaderModule()) {
         moduleCreateInfo.codeSize = strlen(shaderString.c_str());