Fix PR 110066: crash with -pg -static on riscv

The problem -fasynchronous-unwind-tables is on by default for riscv linux
We need turn it off for crt*.o because it would make __EH_FRAME_BEGIN__ point
to .eh_frame data from crtbeginT.o instead of the user-defined object
during static linking.

This turns it off.

OK?

libgcc/ChangeLog:

	* config.host (riscv*-*-linux*): Add t-crtstuff to tmake_file.
	(riscv*-*-freebsd*): Likewise.
	* config/riscv/t-crtstuff: New file.