patch 8.2.2006: .pbtxt files are not recognized

Problem:    .pbtxt files are not recognized.
Solution:   Recognize .pbtxt as protobuf text buffers. (closes #7326)

runtime/filetype.vim

@@ -1305,6 +1305,7 @@ au BufNewFile,BufRead *.pml			setf promela
 
 " Google protocol buffers
 au BufNewFile,BufRead *.proto			setf proto
+au BufNewFile,BufRead *.pbtxt			setf pbtxt
 
 " Protocols
 au BufNewFile,BufRead */etc/protocols		setf protocols

src/testdir/test_filetype.vim

@@ -345,6 +345,7 @@ let s:filename_checks = {
     \ 'papp': ['file.papp', 'file.pxml', 'file.pxsl'],
     \ 'pascal': ['file.pas', 'file.pp', 'file.dpr', 'file.lpr'],
     \ 'passwd': ['any/etc/passwd', 'any/etc/passwd-', 'any/etc/passwd.edit', 'any/etc/shadow', 'any/etc/shadow-', 'any/etc/shadow.edit', 'any/var/backups/passwd.bak', 'any/var/backups/shadow.bak', '/etc/passwd', '/etc/passwd-', '/etc/passwd.edit', '/etc/shadow', '/etc/shadow-', '/etc/shadow.edit', '/var/backups/passwd.bak', '/var/backups/shadow.bak'],
+    \ 'pbtxt': ['file.pbtxt'],
     \ 'pccts': ['file.g'],
     \ 'pdf': ['file.pdf'],
     \ 'perl': ['file.plx', 'file.al', 'file.psgi', 'gitolite.rc', '.gitolite.rc', 'example.gitolite.rc'],

src/version.c

@@ -750,6 +750,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    2006,
 /**/
     2005,
 /**/