gentoo-overlay/sys-libs/libcap/files/libcap-2.21-include.patch

--- a/libcap/libcap.h
+++ b/libcap/libcap.h
@@ -13,6 +13,7 @@
 #include <stdlib.h>
 #include <string.h>
 #include <sys/capability.h>
+#include <sys/prctl.h> /* prctl() */
 
 #ifndef __u8
 #define __u8    unsigned char