Keep the Lua-less build compiling

`cgit_abort_filters` unhooks the Lua write interposer under NO_LUA
too, where neither the hook nor its state exists, so `make NO_LUA=1`
and the default mode of `tools/release-build.sh` have not compiled
since the die path learned to take stdout back from a filter. The
suite now builds that variant into `build/nolua` and runs it, and a
`lua:` filter in such a build is refused with a message naming the
cause instead of an unknown filter type.

1 file changed, 6 insertions, 0 deletions

diff --git a/source/filter.c b/source/filter.c
index f5fb2d5..dd1eaf0 100644
--- a/source/filter.c
+++ b/source/filter.c
@@ -444,8 +444,10 @@ void cgit_abort_filters(void)
 		close(running_exec->old_stdout);
 		running_exec = NULL;
 	}
+#ifndef NO_LUA
 	if (filter_write)
 		unhook_write();
+#endif
 }
 
 static const struct {
@@ -503,5 +505,9 @@ struct cgit_filter *cgit_new_filter(const char *cmd, filter_type filtertype)
 			return filter_specs[i].create(colon + 1, argument_count);
 	}
 
+#ifdef NO_LUA
+	if (len == 3 && !strncmp("lua", cmd, len))
+		die("Built without Lua, cannot run filter %s", cmd);
+#endif
 	die("Invalid filter type: %.*s", (int)len, cmd);
 }