patch 9.0.0055: bitbake files are not detected

Problem:    Bitbake files are not detected.
Solution:   Add bitbake filetype detection by file name and contents. (Gregory
            Anders, closes #10697)

runtime/autoload/dist/ft.vim

@@ -519,12 +519,14 @@ export def FTinc()
     # headers so assume POV-Ray
     elseif lines =~ '^\s*\%({\|(\*\)' || lines =~? ft_pascal_keywords
       setf pascal
+    elseif lines =~# '\<\%(require\|inherit\)\>' || lines =~# '\w\+ = '
+      setf bitbake
     else
       FTasmsyntax()
       if exists("b:asmsyntax")
-	exe "setf " .. fnameescape(b:asmsyntax)
+        exe "setf " .. fnameescape(b:asmsyntax)
       else
-	setf pov
+        setf pov
       endif
     endif
   endif

runtime/filetype.vim

@@ -252,6 +252,9 @@ au BufNewFile,BufRead *.db			call dist#ft#BindzoneCheck('')
 " Blank
 au BufNewFile,BufRead *.bl			setf blank
 
+" Bitbake
+au BufNewFile,BufRead *.bb,*.bbappend,*.bbclass,*/build/conf/*.conf,*/meta{-*,}/conf/*.conf	setf bitbake
+
 " Blkid cache file
 au BufNewFile,BufRead */etc/blkid.tab,*/etc/blkid.tab.old   setf xml