Compatibility: Use org-load-noerror-mustsuffix
* lisp/org-macs.el: New macro to allow the 5-argument form of load to
be used where possible without breaking compatibility with XEmacs.
* lisp/org.el (org-version, org-reload): Use
`org-load-noerror-mustsuffix´ instead of adding a fifth argument to
load directly. Guard against undefined variable load-suffixes,
which doesn't exist in XEmacs.
Since load-suffixes doesn't exist in XEmacs, (org-reload 'uncompiled)
will not work. If it doesn't complicate the compatibility macro too
much this can be added later.