Reduce libslang.so.2 library footprint

@kylerankin : doing some tests to reduce libraries footprints, since x200 and other hardware that don't have a TPM also tend to have smaller SPI flash chips (4mb on some, 8mb on others).

Whiptail depends on a 1.1M libslang.so.2 library, which is the biggest of all, with currently deactivated features:

--with-z=no \
--with-png=no \
--with-pcre=no \
--with-onig=no \

Can we deactivate some other unneeded features? Here is the list:

--with-terminfo=no \
--with-readline=no \
--with-slsyswrap=no \
--with-x=no \
--with-pcre=no \
--with-pcrelib=no \
--with-pcreinc=no \
--with-onig=no \
--with-oniglib=no \
--with-oniginc=no \
--with-png=no \
--with-pnglib=no \
--with-pnginc=no \
--with-z=no \
--with-zlib=no \
--with-zinc=no \
--with-iconv=no \
--with-iconvlib=no \
--with-iconvinc=no \

Edit: even if all of those are turned off, the library still pounds 1.1M. Any advice?