patch 8.2.4571: not all gdb files are recognized

Problem:    Not all gdb files are recognized.
Solution:   Add a few more patterns for gdb. (Jade Lovelace, closes #9956)

runtime/filetype.vim

@@ -668,7 +668,7 @@ au BufNewFile,BufRead *.fs			call dist#ft#FTfs()
 au BufNewFile,BufRead *.fsi,*.fsx		setf fsharp
 
 " GDB command files
-au BufNewFile,BufRead .gdbinit,gdbinit		setf gdb
+au BufNewFile,BufRead .gdbinit,gdbinit,.gdbearlyinit,gdbearlyinit,*.gdb		setf gdb
 
 " GDMO
 au BufNewFile,BufRead *.mo,*.gdmo		setf gdmo

src/testdir/test_filetype.vim

@@ -196,7 +196,7 @@ let s:filename_checks = {
     \ 'fstab': ['fstab', 'mtab'],
     \ 'fusion': ['file.fusion'],
     \ 'fvwm': ['/.fvwm/file', 'any/.fvwm/file'],
-    \ 'gdb': ['.gdbinit', 'gdbinit'],
+    \ 'gdb': ['.gdbinit', 'gdbinit', 'file.gdb', '.config/gdbearlyinit', '.gdbearlyinit'],
     \ 'gdresource': ['file.tscn', 'file.tres'],
     \ 'gdscript': ['file.gd'],
     \ 'gdmo': ['file.mo', 'file.gdmo'],

src/version.c

@@ -750,6 +750,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    4571,
 /**/
     4570,
 /**/