place install file into /usr/portage/disfiles

$ echo “>=dev-java/oracle-jre-bin-1.8.0.77 Oracle-BCLA-JavaSE”>/etc/portage/package.license
$ emerge oracle-jre-bin

emerge –sync

CFLAGS="-march=native -O3 -pipe -fforce-addr -fomit-frame-pointer -fexpensive-optimizations -ffast-math -funroll-loops"
USE="-X -innodb -berkdb -gtk -mariadb -ipv6"
LINGUAS="en cs"

https://wiki.gentoo.org/wiki/Safe_CFLAGS