patch 9.1.0465: missing filecopy() function

Problem:  missing filecopy() function
Solution: implement filecopy() Vim script function
          (Shougo Matsushita)

closes: #12346

Co-authored-by: zeertzjq <zeertzjq@outlook.com>
Signed-off-by: Shougo Matsushita <Shougo.Matsu@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/testdir/Make_all.mak b/src/testdir/Make_all.mak
index a80b130..e31d2b5 100644
--- a/src/testdir/Make_all.mak
+++ b/src/testdir/Make_all.mak
@@ -143,6 +143,7 @@
 	test_file_perm \
 	test_file_size \
 	test_filechanged \
+	test_filecopy \
 	test_fileformat \
 	test_filetype \
 	test_filter_cmd \
@@ -404,6 +405,7 @@
 	test_expr.res \
 	test_file_size.res \
 	test_filechanged.res \
+	test_filecopy.res \
 	test_fileformat.res \
 	test_filetype.res \
 	test_filter_cmd.res \