patch 8.0.1494: no autocmd triggered in Insert mode with visible popup menu

Problem:    No autocmd triggered in Insert mode with visible popup menu.
Solution:   Add TextChangedP. (Prabir Shrestha, Christian Brabandt,
            closes #2372, closes #1691)
            Fix that the TextChanged autocommands are not always triggered
            when sourcing a script.
diff --git a/src/proto/fileio.pro b/src/proto/fileio.pro
index 7579631..12d5c14 100644
--- a/src/proto/fileio.pro
+++ b/src/proto/fileio.pro
@@ -48,6 +48,7 @@
 int has_cursormovedI(void);
 int has_textchanged(void);
 int has_textchangedI(void);
+int has_textchangedP(void);
 int has_insertcharpre(void);
 int has_cmdundefined(void);
 int has_funcundefined(void);