patch 8.2.2639: build failure when fsync() is not available

Problem:    Build failure when fsync() is not available.
Solution:   Add #ifdef.

Author: brammool

src/ui.c

@@ -50,8 +50,10 @@ ui_write(char_u *s, int len, int console UNUSED)
 # endif
 
 	mch_write(s, len);
+# if defined(HAVE_FSYNC)
 	if (console && s[len - 1] == '\n')
-	    fsync(1);
+	    vim_fsync(1);
+# endif
 
 # if !defined(MSWIN)
 	if (output_conv.vc_type != CONV_NONE)

src/version.c

@@ -750,6 +750,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    2639,
 /**/
     2638,
 /**/