patch 9.0.1661: BUCK files are not recognized

Problem:    BUCK files are not recognized.
Solution:   Recognize BUCK files as "bzl". (Son Luong Ngoc, closes #12564)
diff --git a/src/testdir/test_filetype.vim b/src/testdir/test_filetype.vim
index a704fb6..cf74a02 100644
--- a/src/testdir/test_filetype.vim
+++ b/src/testdir/test_filetype.vim
@@ -814,7 +814,7 @@
 def s:GetFilenameCaseChecks(): dict<list<string>>
   return {
     modula2: ['file.DEF'],
-    bzl: ['file.BUILD', 'BUILD'],
+    bzl: ['file.BUILD', 'BUILD', 'BUCK'],
   }
 enddef
 
diff --git a/src/version.c b/src/version.c
index ba99907..437da65 100644
--- a/src/version.c
+++ b/src/version.c
@@ -696,6 +696,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1661,
+/**/
     1660,
 /**/
     1659,