Simplify process exit-code handling on Posix, take 2.

runtime/bin/platform_android.cc

Index: runtime/bin/platform_android.cc
diff --git a/runtime/bin/platform_android.cc b/runtime/bin/platform_android.cc
index e069d5aa5200bf52086ef31719a3b932e5e4607f..dfa2e27ac82cd2dc1ce231e11972883afe687386 100644
--- a/runtime/bin/platform_android.cc
+++ b/runtime/bin/platform_android.cc
@@ -26,14 +26,6 @@ bool Platform::Initialize() {
     perror("Setting signal handler failed");
     return false;
   }
-  // Unblock SIGCHLD as waiting on spawned child process depends
-  // on successful interception of this signal.
-  sigset_t newset;
-  sigemptyset(&newset);
-  sigaddset(&newset, SIGCHLD);
-  if (sigprocmask(SIG_UNBLOCK, &newset, NULL) != 0) {
-    perror("Unblocking SIGCHLD signal failed");
-  }
   return true;
 }