gnulib-tool: Improve handling of multiple --local-dir options. * doc/gnulib.texi (Extending Gnulib): Explain how multiple --local-dir options work. * gnulib-tool (func_path_prepend): Remove function. (func_path_foreach): Make IFS handling more robust. (local_gnulib_path): Collect --local-dir values using func_path_append, not func_path_prepend. (func_determine_path_separator): Make IFS handling more robust. (func_lookup_file_cb): New function. (func_lookup_file): Rewritten to use func_lookup_file_cb instead of func_lookup_local_file. Apply the patches in the reverse order of their origin in $local_gnulib_path. (func_count_relative_local_gnulib_path): Make IFS handling more robust. * NEWS: Mention that the first --local-dir option is the one with highest priority.

# See lib/git-merge-changelog.c for making this useful.
ChangeLog	merge=merge-changelog

# Run this to make 'git diff' on texinfo files give nicer hunk context:
#   git config diff.texinfo.funcname '^@node[	 ][	 ]*\\([^,][^,]*\\)'
*.texi* diff=texinfo