[Bug target/103889] gccgo is unable to find its standard library by default on 64-Bit RISC-V due to musl not using multilib but still uses t-linux

["bau2wux4sh at pkv73 dot anonbox.net" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103889

--- Comment #13 from John Doe <bau2wux4sh at pkv73 dot anonbox.net> ---
(In reply to Andrew Pinski from comment #12)
> Because the Linux-gnu folks will always use lib64 instead of lib here. So
> there is no need to fix gcc/config/riscv/t-linux. There is a LSF on purpose
> which I thought defined this all for *-*-linux-gnu across distros.

What is LSF? Do you mean LSB (Linux Standard Base)? Because the comment in the 
t-linux64 i386 configuration file explicitly states:

> The LSB does not enforce the use of /lib64 and /usr/lib64

I might be repeating myself but other architecture configuration files
explicitly include a check to ensure that this directory exists, e.g.:

> $(if $(wildcard $(shell echo $(SYSTEM_HEADER_DIR))/../../usr/lib32),../lib32,../lib)

Then again I am personally not very familiar with these configuration files, it
just seems odd to me that the RISC-V one doesn't have such a check.