boot: update lua linter for recent module additions

For modules we expect to be there, we need to --globals them in to avoid
linter errors.  Maybe we should switch to a different model for these
to clean up our linter exceptions... 'meh'.

Reported by:	David Cross <david_crossfamilyweb_com>

tools/boot/lua-lint.sh

@@ -17,4 +17,4 @@ cd $(make -V SRCTOP)/stand
 ${LUACHECK} . --globals loader --globals lfs --globals io.getchar \
 	--globals io.ischar --globals printc --globals cli_execute \
 	--globals cli_execute_unparsed --globals try_include \
-	--globals pager --std lua53
+	--globals pager --globals gfx --globals hash --std lua53