define PR_SET_CHILD_SUBREAPER if not set

Docker-DCO-1.1-Signed-off-by: Daniel, Dao Quang Minh <[email protected]> (github: dqminh)

Author: dqminh

namespaces/nsenter/nsenter.c

@@ -15,6 +15,10 @@
 #include <unistd.h>
 #include <getopt.h>
 
+#ifndef PR_SET_CHILD_SUBREAPER
+#define PR_SET_CHILD_SUBREAPER 36
+#endif
+
 static const kBufSize = 256;
 static const char *kNsEnter = "nsenter";