Ignore rt_sigaction() syscalls on x86 and x86_64
Ignore rt_sigaction() syscalls on x86 and x86_64

This is currently how alpha handles this syscall.

This is needed for the gcc spec2k benchmarks to run.

haowu4682/gem5,LingxiaoJIA/gem5,LingxiaoJIA/gem5,haowu4682/gem5,haowu4682/gem5,LingxiaoJIA/gem5,haowu4682/gem5,haowu4682/gem5,LingxiaoJIA/gem5,LingxiaoJIA/gem5,haowu4682/gem5,LingxiaoJIA/gem5,haowu4682/gem5,haowu4682/gem5,LingxiaoJIA/gem5,haowu4682/gem5