Merge branch 'js/find-lib-h-with-ls-files-when-possible'

The Makefile uses 'find' utility to enumerate all the *.h header files, which is expensive on platforms with slow filesystems; it now optionally uses "ls-files" if working within a repository, which is a trick similar to how all sources are enumerated to run ETAGS on. * js/find-lib-h-with-ls-files-when-possible: Makefile: use `git ls-files` to list header files, if possible