[vim] Highlight "arflags"

Change-Id: I847420e63a4adedc6818215c111be32dafd1eebf
Reviewed-on: https://gn-review.googlesource.com/c/gn/+/13640
Reviewed-by: Brett Wilson <brettw@chromium.org>
Commit-Queue: Nico Weber <thakis@chromium.org>

misc/vim/syntax/gn.vim

diff --git a/misc/vim/syntax/gn.vim b/misc/vim/syntax/gn.vim
index 851cec6..df2d0d8 100644
--- a/misc/vim/syntax/gn.vim
+++ b/misc/vim/syntax/gn.vim
@@ -43,7 +43,7 @@
 
 " Variables
 syn keyword     gnVariable all_dependent_configs allow_circular_includes_from
-syn keyword     gnVariable args asmflags assert_no_deps
+syn keyword     gnVariable args arflags asmflags assert_no_deps
 syn keyword     gnVariable cflags cflags_c cflags_cc cflags_objc cflags_objcc
 syn keyword     gnVariable check_includes complete_static_lib configs
 syn keyword     gnVariable data data_deps data_keys defines depfile deps