patch 8.1.1795: no syntax HL after splitting windows with :bufdo

Problem:    No syntax HL after splitting windows with :bufdo. (Yasuhiro
            Matsumoto)
Solution:   Trigger Syntax autocommands in buffers that are active.
            (closes #4761)
diff --git a/src/vim.h b/src/vim.h
index 6f7a11d..02b4c03 100644
--- a/src/vim.h
+++ b/src/vim.h
@@ -698,20 +698,21 @@
 #define NOTDONE			2   /* not OK or FAIL but skipped */
 
 /* flags for b_flags */
-#define BF_RECOVERED	0x01	/* buffer has been recovered */
-#define BF_CHECK_RO	0x02	/* need to check readonly when loading file
-				   into buffer (set by ":e", may be reset by
-				   ":buf" */
-#define BF_NEVERLOADED	0x04	/* file has never been loaded into buffer,
-				   many variables still need to be set */
-#define BF_NOTEDITED	0x08	/* Set when file name is changed after
-				   starting to edit, reset when file is
-				   written out. */
-#define BF_NEW		0x10	/* file didn't exist when editing started */
-#define BF_NEW_W	0x20	/* Warned for BF_NEW and file created */
-#define BF_READERR	0x40	/* got errors while reading the file */
-#define BF_DUMMY	0x80	/* dummy buffer, only used internally */
-#define BF_PRESERVED	0x100	/* ":preserve" was used */
+#define BF_RECOVERED	0x01	// buffer has been recovered
+#define BF_CHECK_RO	0x02	// need to check readonly when loading file
+				// into buffer (set by ":e", may be reset by
+				// ":buf"
+#define BF_NEVERLOADED	0x04	// file has never been loaded into buffer,
+				// many variables still need to be set
+#define BF_NOTEDITED	0x08	// Set when file name is changed after
+				// starting to edit, reset when file is
+				// written out.
+#define BF_NEW		0x10	// file didn't exist when editing started
+#define BF_NEW_W	0x20	// Warned for BF_NEW and file created
+#define BF_READERR	0x40	// got errors while reading the file
+#define BF_DUMMY	0x80	// dummy buffer, only used internally
+#define BF_PRESERVED	0x100	// ":preserve" was used
+#define BF_SYN_SET	0x200	// 'syntax' option was set
 
 /* Mask to check for flags that prevent normal writing */
 #define BF_WRITE_MASK	(BF_NOTEDITED + BF_NEW + BF_READERR)