patch 9.0.1106: not all postfix files are recognized

Problem:    Not all postfix files are recognized.
Solution:   Recognize main.cf.proto files. (closes #11732)

src/testdir/test_filetype.vim

@@ -420,7 +420,7 @@ let s:filename_checks = {
     \ 'pdf': ['file.pdf'],
     \ 'perl': ['file.plx', 'file.al', 'file.psgi', 'gitolite.rc', '.gitolite.rc', 'example.gitolite.rc', '.latexmkrc', 'latexmkrc'],
     \ 'pf': ['pf.conf'],
-    \ 'pfmain': ['main.cf'],
+    \ 'pfmain': ['main.cf', 'main.cf.proto'],
     \ 'php': ['file.php', 'file.php9', 'file.phtml', 'file.ctp', 'file.phpt', 'file.theme'],
     \ 'pike': ['file.pike', 'file.pmod'],
     \ 'pilrc': ['file.rcp'],

src/version.c

@@ -695,6 +695,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1106,
 /**/
     1105,
 /**/