patch 8.2.4766: KRL files using "deffct" not recognized

Problem:    KRL files using "deffct" not recognized.
Solution:   Adjust the pattern used for matching. (Patrick Meiser-Knosowski,
            closes #10200)
diff --git a/src/testdir/test_filetype.vim b/src/testdir/test_filetype.vim
index a94002e..1bc94b5 100644
--- a/src/testdir/test_filetype.vim
+++ b/src/testdir/test_filetype.vim
@@ -768,7 +768,7 @@
 endfunc
 
 """""""""""""""""""""""""""""""""""""""""""""""""
-" Tests for specific extentions and filetypes.
+" Tests for specific extensions and filetypes.
 " Keep sorted.
 """""""""""""""""""""""""""""""""""""""""""""""""
 
@@ -1562,11 +1562,13 @@
   bwipe!
   call delete('srcfile.Src')
 
-  " KRL global def with embedded spaces, file starts with empty line(s).
-  call writefile(['', 'global  def  srcfile()'], 'srcfile.SRC')
-  split srcfile.SRC
-  call assert_equal('krl', &filetype)
-  bwipe!
+  " KRL global deffct with embedded spaces, file starts with empty line(s).
+  for text in ['global  def  srcfile()', 'global  deffct  srcfile()']
+    call writefile(['', text], 'srcfile.SRC')
+    split srcfile.SRC
+    call assert_equal('krl', &filetype, text)
+    bwipe!
+  endfor
 
   " User may overrule file inspection
   let g:filetype_src = 'src'
diff --git a/src/version.c b/src/version.c
index d4410d0..c3aad48 100644
--- a/src/version.c
+++ b/src/version.c
@@ -747,6 +747,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    4766,
+/**/
     4765,
 /**/
     4764,