Add out-of-the-box cross-compiling support for riscv64gc-unknown-linux-gnu
Gbp-Pq: Name u-riscv64-cc-465.patch
"riscv32imc-unknown-none-elf" => Some("riscv32-unknown-elf"),
"riscv64gc-unknown-none-elf" => Some("riscv64-unknown-elf"),
"riscv64imac-unknown-none-elf" => Some("riscv64-unknown-elf"),
+ "riscv64gc-unknown-linux-gnu" => Some("riscv64-linux-gnu"),
"s390x-unknown-linux-gnu" => Some("s390x-linux-gnu"),
"sparc-unknown-linux-gnu" => Some("sparc-linux-gnu"),
"sparc64-unknown-linux-gnu" => Some("sparc64-linux-gnu"),