Install libgcc-8-dev-riscv64-cross by entering the following commands in the terminal:
sudo apt update sudo apt install libgcc-8-dev-riscv64-cross
Description:
GCC support library (development files)
This package contains the headers and static library files necessary for building C programs which use libgcc, libgomp, libquadmath, libssp or libitm.
Homepage: http://gcc.gnu.org/
Version: 8-20180414-1ubuntu2cross1
Section: universe/libdevel