You receive this bug because this package does not respect my '-O' system's CFLAGS x86_64-pc-linux-gnu-g++ -march=native -O2 -g0 -pipe -march=native -O2 -pipe -Wall -ansi -pedantic -I -Wno-uninitialized -Wno-unused-parameter -O2 -fPIC -MM -c src/HashPolynomial.cpp > bin/shared/HashPolynomial.d.tmp Last -O2 overwrites my set.
Fixed in current ebuild.