Patch by Ian Charnas from issue 3517.
Add F_FULLFSYNC if it exists (OS X only so far).
diff --git a/Modules/fcntlmodule.c b/Modules/fcntlmodule.c
index 0c85f47..ab7f22d 100644
--- a/Modules/fcntlmodule.c
+++ b/Modules/fcntlmodule.c
@@ -530,6 +530,11 @@
if (ins(d, "F_SHLCK", (long)F_SHLCK)) return -1;
#endif
+/* OS X (and maybe others) let you tell the storage device to flush to physical media */
+#ifdef F_FULLFSYNC
+ if (ins(d, "F_FULLFSYNC", (long)F_FULLFSYNC)) return -1;
+#endif
+
/* For F_{GET|SET}FL */
#ifdef FD_CLOEXEC
if (ins(d, "FD_CLOEXEC", (long)FD_CLOEXEC)) return -1;