unknown pseudo-op: `.attribute`

[nickdesaulniers]

via: https://travis-ci.com/github/ClangBuiltLinux/continuous-integration/jobs/311246235

/tmp/empty-955e67.s: Assembler messages:
/tmp/empty-955e67.s:2: Error: unknown pseudo-op: `.attribute'
/tmp/empty-955e67.s:3: Error: unknown pseudo-op: `.attribute'

[nathanchance]

+ riscv64-linux-gnu-as --version

I'll switch us over to the integrated assembler: nathanchance/continuous-integration@6d1cdb4

[MaskRay]

RISC-V attribute section was committed yesterday https://reviews.llvm.org/D74023

[nathanchance]

I assume a newer version of binutils supports that but our Docker image is stuck with 2.31.1 since that is the latest version from Debian stable. Could jump on unstable to get 2.34 but I think I'd rather just turn on the integrated assembler and use older binutils until we are absolutely forced to jump forward.

As it stands, I think RISCV only needs binutils for ld.bfd due to a problem with ld.lld (#805). It should use all of the other tools no problem.