patch 9.0.1393: Cairo files are not recognized

Problem:    Cairo files are not recognized.
Solution:   Add a pattern for Cairo files. (Amaan Qureshi, closes #12118)

runtime/filetype.vim

@@ -277,6 +277,9 @@ endif
 au BufNewFile,BufRead *.c			call dist#ft#FTlpc()
 au BufNewFile,BufRead *.lpc,*.ulpc		setf lpc
 
+" Cairo
+au BufNewFile,BufRead *.cairo			setf cairo
+
 " Calendar
 au BufNewFile,BufRead calendar			setf calendar
 

src/testdir/test_filetype.vim

@@ -96,6 +96,7 @@ let s:filename_checks = {
     \ 'cabal': ['file.cabal'],
     \ 'cabalconfig': ['cabal.config'],
     \ 'cabalproject': ['cabal.project', 'cabal.project.local'],
+    \ 'cairo': ['file.cairo'],
     \ 'calendar': ['calendar', '/.calendar/file', '/share/calendar/any/calendar.file', '/share/calendar/calendar.file', 'any/share/calendar/any/calendar.file', 'any/share/calendar/calendar.file'],
     \ 'capnp': ['file.capnp'],
     \ 'catalog': ['catalog', 'sgml.catalogfile', 'sgml.catalog', 'sgml.catalog-file'],

src/version.c

@@ -695,6 +695,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1393,
 /**/
     1392,
 /**/