As described in Gentoo's bugzilla, http://bugs.gentoo.org/show_bug.cgi?id=185684,

Because libart_lgpl tries to run the result of the compiled gen_art_config.c to generate art_config.h, libart fails to cross compile (since is trying to run an ARM binary on  an Intel machine).

======================================

./configure --prefix=/usr --host=arm-softfloat-linux-uclibc
--mandir=/usr/share/man --infodir=/usr/share/info --datadir=/usr/share
--sysconfdir=/etc --localstatedir=/var/lib --build=i486-pc-linux-gnu

checking for arm-softfloat-linux-uclibc-gcc... arm-softfloat-linux-uclibc-gcc

checking whether arm-softfloat-linux-uclibc-gcc accepts -g... yes
checking for arm-softfloat-linux-uclibc-gcc option to accept ISO C89... none
needed


checking build system type... i486-pc-linux-gnu
checking host system type... arm-softfloat-linux-uclibc


checking for arm-softfloat-linux-uclibc-g++... arm-softfloat-linux-uclibc-g++
checking whether we are using the GNU C++ compiler... yes


checking for gfortran... gfortran
configure: WARNING: In the future, Autoconf will not detect cross-tools
whose name does not start with the host triplet.  If you think this
configuration is useful to you, please write to autoconf@gnu.org.


configure: creating ./config.status
config.status: creating libart-features.h
config.status: creating Makefile
config.status: creating libart-2.0.pc
config.status: creating libart-2.0-uninstalled.pc
config.status: creating libart-zip
config.status: creating libart-config
config.status: creating config.h
config.status: executing depfiles commands
arm-softfloat-linux-uclibc-gcc -DHAVE_CONFIG_H -I. -I. -I. -DLIBART_COMPILATION
   -Os -pipe -Wall -Wmissing-prototypes -MT gen_art_config.o -MD -MP -MF
.deps/gen_art_config.Tpo -c -o gen_art_config.o gen_art_config.c
mv -f .deps/gen_art_config.Tpo .deps/gen_art_config.Po
/bin/sh ./libtool --tag=CC   --mode=link arm-softfloat-linux-uclibc-gcc  -Os
-pipe -Wall -Wmissing-prototypes   -o gen_art_config gen_art_config.o
mkdir .libs
arm-softfloat-linux-uclibc-gcc -Os -pipe -Wall -Wmissing-prototypes -o
gen_art_config gen_art_config.o
./gen_art_config > art_config.h
/bin/sh: ./gen_art_config: cannot execute binary file
make: *** [art_config.h] Error 126


=========================================

The header is pretty simple and it can be avoided entirely by using stdint.h or inttypes.h in art_misc.h, but I fear that some apps include this file directly (as a search for 'include art_config.h' suggests.


This is what the generated header looks like on Intel x86:
/* Automatically generated by gen_art_config.c */

#define ART_SIZEOF_CHAR 1
#define ART_SIZEOF_SHORT 2
#define ART_SIZEOF_INT 4
#define ART_SIZEOF_LONG 4

typedef unsigned char art_u8;
typedef unsigned short art_u16;
typedef unsigned int art_u32;

The ART_SIZEOF_* definitions are not used at all in the source so I commented them out in the patch I proposed.

The new art_config.h file loks like this:


$ cat art_config.h
#include <stdint.h>

/* it looks like these definitions are not used at all */
/*
#define ART_SIZEOF_CHAR 1
#define ART_SIZEOF_SHORT 2
#define ART_SIZEOF_INT 4
#define ART_SIZEOF_LONG 4
*/


typedef uint8_t art_u8;
typedef uint16_t art_u16;
typedef uint32_t art_u32;



I made a patch and applied it over trunk. After that, the package cross compiled fine.