doc about VPATH limitation on SunOS

[Alexandre Duret-Lutz]

The present Autoconf documentation reads

| Limitations of Make
| ===================
| [...]
| `VPATH'
|      Don't use it!  For instance any assignment to `VPATH' causes Sun
|      `make' to only execute the first set of double-colon rules.

Akim pasted this comment here from acgeneral.m4 where it was
added six years ago:

| Fri Mar 18 00:43:21 1994  David J. MacKenzie  (address@hidden)
| 
|         * acgeneral.m4 (AC_OUTPUT): Remove VPATH lines if srcdir=., to
|         work around Sun make bug.  From Karl Berry.

Does it still applies ?  How can I reproduce this ?
I'd like to upgrade this section with other VPATH limitations
but I do not understand this one.

-- 
Alexandre Duret-Lutz