Update runtime files.
diff --git a/runtime/syntax/c.vim b/runtime/syntax/c.vim
index 3648860..7925e88 100644
--- a/runtime/syntax/c.vim
+++ b/runtime/syntax/c.vim
@@ -1,7 +1,7 @@
" Vim syntax file
" Language: C
" Maintainer: Bram Moolenaar <Bram@vim.org>
-" Last Change: 2020 Aug 11
+" Last Change: 2020 Aug 28
" Quit when a (custom) syntax file was already loaded
if exists("b:current_syntax")
@@ -346,6 +346,8 @@
syn keyword cConstant SIGSTOP SIGTERM SIGTRAP SIGTSTP SIGTTIN SIGTTOU SIGUSR1 SIGUSR2
syn keyword cConstant _IOFBF _IOLBF _IONBF BUFSIZ EOF WEOF FOPEN_MAX FILENAME_MAX L_tmpnam
syn keyword cConstant SEEK_CUR SEEK_END SEEK_SET TMP_MAX stderr stdin stdout EXIT_FAILURE EXIT_SUCCESS RAND_MAX
+ " used in assert.h
+ syn keyword cConstant NDEBUG
" POSIX 2001
syn keyword cConstant SIGBUS SIGPOLL SIGPROF SIGSYS SIGURG SIGVTALRM SIGXCPU SIGXFSZ
" non-POSIX signals