security/wpa_supplicant-devel: Make use of fdatasync(2)

FreeBSD has supported fdatasync(2) since FreeBSD 11.1. Prepare for
future use when syncing to planned updates to base.

security/wpa_supplicant-devel/files/patch-src_utils_os__unix.c

@@ -0,0 +1,14 @@
+--- src/utils/os_unix.c.orig	2021-06-02 14:11:18.000000000 -0700
++++ src/utils/os_unix.c	2021-06-07 16:07:39.152547000 -0700
+@@ -464,9 +464,9 @@
+ int os_fdatasync(FILE *stream)
+ {
+ 	if (!fflush(stream)) {
+-#ifdef __linux__
++#if defined __FreeBSD__ || defined __linux__
+ 		return fdatasync(fileno(stream));
+-#else /* !__linux__ */
++#else /* !__linux__ && !__FreeBSD__ */
+ #ifdef F_FULLFSYNC
+ 		/* OS X does not implement fdatasync(). */
+ 		return fcntl(fileno(stream), F_FULLFSYNC);