patch 8.2.0852: cannot map CTRL-S on some systems

Problem:    Cannot map CTRL-S on some systems.
Solution:   Do not use CTRL-S for flow control.
diff --git a/src/os_unix.c b/src/os_unix.c
index 3464426..e1296c4 100644
--- a/src/os_unix.c
+++ b/src/os_unix.c
@@ -3482,11 +3482,9 @@
     {
 	// ~ICRNL enables typing ^V^M
 	tnew.c_iflag &= ~ICRNL;
-# ifdef IXON_NOT_USED
 	// Do not make CTRL-S stop output, for most users it is unexpected and
 	// is hardly ever useful.
 	tnew.c_iflag |= IXON;
-# endif
 	tnew.c_lflag &= ~(ICANON | ECHO | ISIG | ECHOE
 # if defined(IEXTEN) && !defined(__MINT__)
 		    | IEXTEN	    // IEXTEN enables typing ^V on SOLARIS
diff --git a/src/version.c b/src/version.c
index da31699..f60d1a4 100644
--- a/src/version.c
+++ b/src/version.c
@@ -747,6 +747,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    852,
+/**/
     851,
 /**/
     850,