add fsync to try to get complete skps from webpage picture capture

src/ports/SkOSFile_stdio.cpp

Index: src/ports/SkOSFile_stdio.cpp
diff --git a/src/ports/SkOSFile_stdio.cpp b/src/ports/SkOSFile_stdio.cpp
index 3371bb7031b7b1c871560a564139a4ad54dc5e3e..ecd5a027fcd82618d371b136c43e7b4f200f02bb 100644
--- a/src/ports/SkOSFile_stdio.cpp
+++ b/src/ports/SkOSFile_stdio.cpp
@@ -143,6 +143,14 @@ void sk_fflush(FILE* f) {
     ::fflush(f);
 }
 
+void sk_fsync(FILE* f) {
+#if !defined(_WIN32) && !defined(SK_BUILD_FOR_ANDROID) && !defined(__UCLIBC__) \
+        && !defined(_NEWLIB_VERSION)
+    int fd = ::fileno(f);
+    ::fsync(fd);
+#endif
+}
+
 bool sk_fseek(FILE* f, size_t byteCount) {
     int err = ::fseek(f, (long)byteCount, SEEK_SET);
     return err == 0;