gcc/
	PR target/84797
	* config.gcc (riscv*-*-*): Handle --with-multilib-list.
	* config/riscv/t-withmultilib: New.
	* config/riscv/withmultilib.h: New.
	* doc/install.texi: Document RISC-V --with-multilib-list support.

From-SVN: r260096