The current beahaviour is IMHO actually correct. There is no need for checking
if /usr/lib/libiconv.so exists, because on some systems (eg. Irix, or
GNU libc) there is no separate libiconv and the functionality is
provided by libc.

The bug lies in texinfo's configure script, which assumes that both
include/iconv.h and lib/libiconv.so exist. On systems without iconv
separate, but with its functionality provided in libc, this is obviously
incorrect.

This bug persists even if --with-libiconv-prefix=... is removed from the
Makefile.

I think configure can detect what library is needed for iconv
functionality, but for some reason, INTLLIBS variable is set to 
'-L/usr/pkg/lib -Wl,-R/usr/pkg/lib -lintl -liconv' without performing
this test.

I don't understand how this is supposed to work on Linux which also
doesn't have libiconv.so .

BTW, how is possible that /usr/include/iconv.h exists on your system, if
you are using NetBSD 1.6 ? This file should not be present.

I also think that Class: for this bug should be set to sw-bug and
Priority: and Severity: set higher, because as it is, it doesn't work.

(I'm trying it on IRIX.)