patch 9.0.0583: only recognizing .m3u8 files is inconsistent

Problem:    Only recognizing .m3u8 files is inconsistent.
Solution:   Also matc .m3u files. (issue #11204)

runtime/filetype.vim

@@ -844,8 +844,8 @@ au BufNewFile,BufRead *.hex,*.h32		setf hex
 " Hjson
 au BufNewFile,BufRead *.hjson			setf hjson
 
-" HLS Playlist
-au BufNewFile,BufRead *.m3u8			setf hlsplaylist
+" HLS Playlist (or another form of playlist)
+au BufNewFile,BufRead *.m3u,*.m3u8		setf hlsplaylist
 
 " Hollywood
 au BufRead,BufNewFile *.hws			setf hollywood

src/testdir/test_filetype.vim

@@ -255,7 +255,7 @@ let s:filename_checks = {
     \ 'hex': ['file.hex', 'file.h32'],
     \ 'hgcommit': ['hg-editor-file.txt'],
     \ 'hjson': ['file.hjson'],
-    \ 'hlsplaylist': ['file.m3u8'],
+    \ 'hlsplaylist': ['file.m3u', 'file.m3u8'],
     \ 'hog': ['file.hog', 'snort.conf', 'vision.conf'],
     \ 'hollywood': ['file.hws'],
     \ 'hoon': ['file.hoon'],

src/version.c

@@ -699,6 +699,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    583,
 /**/
     582,
 /**/