https://gcc.gnu.org/pub/gcc/releases/gcc-9.2.0/gcc-9.2.0.tar.xz gcc
https://gmplib.org/download/gmp/gmp-6.1.2.tar.xz gcc/gmp
https://www.mpfr.org/mpfr-current/mpfr-4.0.2.tar.xz gcc/mpfr
https://ftp.gnu.org/gnu/mpc/mpc-1.1.0.tar.gz gcc/mpc
files/c99