[gentoo-embedded] New patch for add support "-a" options and one stage.

Hi!!!
This patch add one stage(-s1, --stage1 Also build kernel and libc
headers) betwen 0 and 1 stage, for available this trick:

crossdev -S --ex-gdb --g 4.2.4 -v -t armv4tl-maverick-linux-gnueabi -s1
EXTRA_ECONF="--with-cpu=arm920t --with-tune=arm920t --with-fpu=maverick
--with-float-abi=softfp" crossdev -S --ex-gdb --g 4.2.4 -v -t
armv4tl-maverick-linux-gnueabi -s2
crossdev -S --ex-gdb --g 4.2.4 -v -t armv4tl-maverick-linux-gnueabi -s4
EXTRA_ECONF="--with-cpu=arm920t --with-tune=arm920t --with-fpu=maverick
--with-float-abi=softfp" crossdev -S --ex-gdb --g 4.2.4 -v -t
armv4tl-maverick-linux-gnueabi -s5