multilib support

[Simon Stelling]

Hi,

It seems like libtool has some problems on multilib-enabled systems.

When libtool is given a -l argument is tries to find a matching libtool 
archive by searching through various paths:

for searchdir in '$newlib_search_path' '$lib_search_path' 
'$sys_lib_search_path' '$shlib_search_path'

if $searchdir/lib$NAME.la can be found, it is sourced, resulting in:

libdir=/usr/lib64

so that libtool will take the absolute path to specify the .so:

x86_64-pc-linux-gnu-gcc -O2 -pipe -Wl,-z -Wl,now -o passwd passwd.o
../libmisc/libmisc.a ../lib/.libs/libshadow.a -lcrypt -lpam -lpam_misc
${libdir}/libcrack.so

The problem obviously is that libtool sources .la without checking 
whether the corresponding shared library has the same bitness as the 
piece of software it is going to build. This results in lines as above, 
leading to error messages like this one:

/usr/lib/gcc/x86_64-pc-linux-gnu/3.4.4/../../../../x86_64-pc-linux-gnu/bin/ld:
skipping incompatible /lib64/libcrack.so when searching for 
/lib64/libcrack.so
/usr/lib/gcc/x86_64-pc-linux-gnu/3.4.4/../../../../x86_64-pc-linux-gnu/bin/ld:
cannot find /lib64/libcrack.so

Note that this issue is also covered in the Gentoo bug 124763 [1]. I 
hope I described the problem detailed enough. If there is any useful 
info I can provide, let me know.

[1] http://bugs.gentoo.org/show_bug.cgi?id=124763

--
Kind Regards,

Simon Stelling
Gentoo/AMD64 Developer