[tlbuild] missing libiconv when compiling xdvik on FreeBSD

[Bruno Haible]

Hi Mojca,

> This is because libiconv's iconv.h does:
> 
>     #define iconv_open libiconv_open
>     ...
>     #define iconv_close libiconv_close

Yes, these definitions are there to signal a mismatch between libiconv and
the system's iconv early, namely to provoke a link error rather than a crash
at run time.

> Now, xdvi on checks the first one, realizes that one doesn't need to
> add -liconv, but then another dependency needs -I/usr/local/include
> and that breaks the build.

The fix should be to reorder the configure.ac file, so that macros that
augment $CPPFLAGS come early.

> I was pointed to
>     https://www.gnu.org/software/gettext/manual/html_node/AM_005fICONV.html
> which is considered an "upstream" version that is supposed to take
> care of all these strange iconv anomalies.
> 
> So I took an upstream copy of iconv.m4, put it to
> texk/xdvik/m4/iconv.m4 and made the following change:
> 
> --- texk/xdvik/configure.ac (revision 47244)
> +++ texk/xdvik/configure.ac (working copy)
> @@ -114,7 +114,7 @@
>  AC_CHECK_HEADERS([netdb.h sys/bsdtypes.h sys/param.h unistd.h
> sys/fcntl.h regex.h])
> 
>  # Checks for iconv
> -XDVI_CHECK_ICONV
> +AM_ICONV
> 
>  # Checks for langinfo
>  XDVI_CHECK_LANGINFO
> 
> I was then stuck because apparently I didn't run all the autofoo magic
> correctly.
> 
> automake
> configure.ac:117: error: required file '../../build-aux/config.rpath' not found

iconv.m4 is nowadays better packaged in gnulib.

To import it, either use gnulib-tool (probably overkill in this case) or copy
the following files from gnulib:

m4/iconv.m4
m4/lib-ld.m4
m4/lib-link.m4
m4/lib-prefix.m4
m4/host-cpu-c-abi.m4
m4/asm-underscore.m4
build-aux/config.rpath

Bruno