[libc][POSIX][RISCV] RV32 fails clock_settime test

[amemov]

RV32 buildbot fails when clock_settime test executes. Function should be excluded from RV32 targets

[llvmbot]

@llvm/issue-subscribers-libc

Author: Anton Shepelev (amemov)

RV32 buildbot fails when `clock_settime` test executes. Function should be excluded from RV32 targets