Better collection of zombie processes.

Note that there seems to be a deadlock if a process exits when there are
zombies around. Init also doesn't handle zombie children correctly as there
is sent no SIGCHLD signal yet.

utils/init.cpp

@@ -58,7 +58,9 @@ int runsystem()
 		return status;
 	}
 
-	return child();
+	int ret = child();
+	while ( 0 < waitpid(-1, NULL, WNOHANG) );
+	return ret;
 }
 
 int main(int argc, char* argv[])

utils/mxsh.cpp

@@ -79,6 +79,9 @@ int runcommandline(const char** tokens)
 	bool internal;
 	int internalresult;
 readcmd:
+	// Collect any pending zombie processes.
+	while ( 0 < waitpid(-1, NULL, WNOHANG) );
+
 	cmdstart = cmdnext;
 	for ( cmdend = cmdstart; true; cmdend++ )
 	{