patch 8.0.1394: cannot intercept a yank command

Problem:    Cannot intercept a yank command.
Solution:   Add the TextYankPost autocommand event. (Philippe Vaucher et al.,
            closes #2333)
diff --git a/src/vim.h b/src/vim.h
index b43c210..4765b78 100644
--- a/src/vim.h
+++ b/src/vim.h
@@ -1339,6 +1339,7 @@
     EVENT_TEXTCHANGEDI,		/* text was modified in Insert mode*/
     EVENT_CMDUNDEFINED,		/* command undefined */
     EVENT_OPTIONSET,		/* option was set */
+    EVENT_TEXTYANKPOST,		/* after some text was yanked */
     NUM_EVENTS			/* MUST be the last one */
 };
 
@@ -1988,7 +1989,8 @@
 #define VV_TERMU7RESP	83
 #define VV_TERMSTYLERESP 84
 #define VV_TERMBLINKRESP 85
-#define VV_LEN		86	/* number of v: vars */
+#define VV_EVENT	86
+#define VV_LEN		87	/* number of v: vars */
 
 /* used for v_number in VAR_SPECIAL */
 #define VVAL_FALSE	0L