init: Introduce the function ReapAndRemove()

Prepare for adding a second caller of ReapAndRemove().

Change-Id: I0f54af6136f49caa0198c123a4c8de968e5f41ba
Signed-off-by: Bart Van Assche <bvanassche@google.com>
diff --git a/init/sigchld_handler.h b/init/sigchld_handler.h
index e07a7d6..5351302 100644
--- a/init/sigchld_handler.h
+++ b/init/sigchld_handler.h
@@ -18,12 +18,13 @@
 #define _INIT_SIGCHLD_HANDLER_H_
 
 #include <chrono>
+#include <set>
 #include <vector>
 
 namespace android {
 namespace init {
 
-void ReapAnyOutstandingChildren();
+std::set<pid_t> ReapAnyOutstandingChildren();
 
 void WaitToBeReaped(int sigchld_fd, const std::vector<pid_t>& pids,
                     std::chrono::milliseconds timeout);