patch 8.2.1885: filetype tests unnessarily creates swap files

Problem:    Filetype tests unnessarily creates swap files.
Solution:   Disable 'swapfile'. (Ken Takata, closes #7183)

src/testdir/test_filetype.vim

@@ -549,6 +549,7 @@ let s:filename_case_checks = {
     \ }
 
 func CheckItems(checks)
+  set noswapfile
   for [ft, names] in items(a:checks)
     for i in range(0, len(names) - 1)
       new
@@ -565,6 +566,7 @@ func CheckItems(checks)
       bwipe!
     endfor
   endfor
+  set swapfile&
 endfunc
 
 func Test_filetype_detection()

src/version.c

@@ -750,6 +750,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1885,
 /**/
     1884,
 /**/