[tlbuild] xdvik update broke builds on Solaris

[Mojca Miklavec]

Hi,

The xdvik update broke Solaris builds due to undefined strnlen

../../../texk/xdvik/main.c:458:13: warning: implicit declaration of
function 'strnlen' [-Wimplicit-function-declaration]
  size_t n = strnlen(real_filename, MAXPATHLEN);
             ^
/bin/bash ./libtool  --tag=CC   --mode=link /opt/csw/bin/gcc-5.5
-Wimplicit -Wreturn-type -Wdeclaration-after-statement
-Wno-unknown-pragmas -g -O2   -o xdvi-bin main.o libxdvi.a
/path/to/Work/texk/kpathsea/libkpathsea.la
/path/to/Work/libs/freetype2/libfreetype.a  -Xlinker
--allow-multiple-definition  -lXaw -lXmu -lXt -lSM -lICE -lXext -lXpm
-lX11 -lsocket  -lnsl  -lm
libtool: link: /opt/csw/bin/gcc-5.5 -Wimplicit -Wreturn-type
-Wdeclaration-after-statement -Wno-unknown-pragmas -g -O2 -o xdvi-bin
main.o -Wl,--allow-multiple-definition  libxdvi.a
/path/to/Work/texk/kpathsea/.libs/libkpathsea.a
/path/to/Work/libs/freetype2/libfreetype.a -lXaw -lXmu -lXt -lSM -lICE
-lXext -lXpm -lX11 -lsocket -lnsl -lm
Undefined first referenced
 symbol      in file
strnlen                             main.o

Mojca