[compiler-rt] [NFCI][sanitizer] Refactor SIGNAL_INTERCEPTOR_SIGACTION_IMPL to not immediately return (PR #162916)

[Vitaly Buka via llvm-commits]

================
@@ -68,7 +77,10 @@ INTERCEPTOR(int, sigaction_symname, int signum,
     if (!oldact) return 0;
     act = nullptr;
   }
+
+  uptr ret;
   SIGNAL_INTERCEPTOR_SIGACTION_IMPL(signum, act, oldact);
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vitalybuka wrote:

can we make it 
return SIGNAL_INTERCEPTOR_SIGACTION_IMPL(signum, act, oldact);?

https://github.com/llvm/llvm-project/pull/162916