vim: add `norecurse` attribute

Add missing attribute to the keyword set.

llvm-svn: 284270
diff --git a/llvm/utils/vim/syntax/llvm.vim b/llvm/utils/vim/syntax/llvm.vim
index 4756882..8fb2236 100644
--- a/llvm/utils/vim/syntax/llvm.vim
+++ b/llvm/utils/vim/syntax/llvm.vim
@@ -109,6 +109,7 @@
       \ noimplicitfloat
       \ noinline
       \ nonlazybind
+      \ norecurse
       \ noredzone
       \ noreturn
       \ nounwind