Add unistd.h include to GrVkGpu.cpp on unix for sleep

Fixes Fuchsia build

Change-Id: Ieb3b7092586495f5153ba18d14a94d8dcdab1dbd
Reviewed-on: https://skia-review.googlesource.com/10261
Reviewed-by: Mike Klein <mtklein@chromium.org>
Commit-Queue: Mike Klein <mtklein@chromium.org>
diff --git a/src/gpu/vk/GrVkGpu.cpp b/src/gpu/vk/GrVkGpu.cpp
index 7419f15..7676964 100644
--- a/src/gpu/vk/GrVkGpu.cpp
+++ b/src/gpu/vk/GrVkGpu.cpp
@@ -39,6 +39,10 @@
 
 #include "SkSLCompiler.h"
 
+#if !defined(SK_BUILD_FOR_WIN)
+#include <unistd.h>
+#endif // !defined(SK_BUILD_FOR_WIN)
+
 #define VK_CALL(X) GR_VK_CALL(this->vkInterface(), X)
 #define VK_CALL_RET(RET, X) GR_VK_CALL_RET(this->vkInterface(), RET, X)
 #define VK_CALL_ERRCHECK(X) GR_VK_CALL_ERRCHECK(this->vkInterface(), X)