emerge error on which-2.19

make[2]: Entering directory `/var/tmp/portage/sys-apps/which-2.19/work/which-2.19/tilde'
source='tilde.c' object='tilde.o' libtool=no \
DEPDIR=.deps depmode=none /bin/sh ../depcomp \
i686-pc-linux-gnu-gcc -DHAVE_CONFIG_H -I. -I. -I.. -mtune=pentium-m -march=pentium-m -O2 -pipe -fomit-frame-pointer -msse2 -msse -mmmx -mfpmath=sse -c tilde.c
source='shell.c' object='shell.o' libtool=no \
DEPDIR=.deps depmode=none /bin/sh ../depcomp \
i686-pc-linux-gnu-gcc -DHAVE_CONFIG_H -I. -I. -I.. -mtune=pentium-m -march=pentium-m -O2 -pipe -fomit-frame-pointer -msse2 -msse -mmmx -mfpmath=sse -c shell.c
Unknown depmode none
make[2]: *** [tilde.o] Error 1
make[2]: *** Waiting for unfinished jobs....
Unknown depmode none
make[2]: *** [shell.o] Error 1
make[2]: Leaving directory `/var/tmp/portage/sys-apps/which-2.19/work/which-2.19/tilde'
make[1]: *** [all-recursive] Error 1
make[1]: Leaving directory `/var/tmp/portage/sys-apps/which-2.19/work/which-2.19'
make: *** [all] Error 2
*
* ERROR: sys-apps/which-2.19 failed.
* Call stack:
* ebuild.sh, line 49: Called src_compile
* environment, line 2050: Called die
* The specific snippet of code:
* emake || die "emake failed";
* The die message:
* emake failed

when use this
am_cv_CC_dependencies_compiler_type=gcc3 emerge which
all things goes well