This is the diff for generated sources after applying:
https://github.com/gentoo/pax-utils/pull/2

diff -ru pax-utils-HEAD.orig/config.h.in pax-utils-HEAD/config.h.in
--- pax-utils-HEAD.orig/config.h.in	2017-04-18 16:26:42.000000000 +0200
+++ pax-utils-HEAD/config.h.in	2017-04-18 16:28:05.000000000 +0200
@@ -526,6 +526,9 @@
 /* Define to 1 if you have the `link' function. */
 #undef HAVE_LINK
 
+/* Define to 1 if you have the <linux/securebits.h> header file. */
+#undef HAVE_LINUX_SECUREBITS_H
+
 /* Define to 1 if the system has the type 'long long int'. */
 #undef HAVE_LONG_LONG_INT
 
diff -ru pax-utils-HEAD.orig/configure pax-utils-HEAD/configure
--- pax-utils-HEAD.orig/configure	2017-04-18 16:26:41.000000000 +0200
+++ pax-utils-HEAD/configure	2017-04-18 16:28:03.000000000 +0200
@@ -34537,6 +34537,19 @@
 
 
 
+for ac_header in linux/securebits.h
+do :
+  ac_fn_c_check_header_mongrel "$LINENO" "linux/securebits.h" "ac_cv_header_linux_securebits_h" "$ac_includes_default"
+if test "x$ac_cv_header_linux_securebits_h" = xyes; then :
+  cat >>confdefs.h <<_ACEOF
+#define HAVE_LINUX_SECUREBITS_H 1
+_ACEOF
+
+fi
+
+done
+
+
 ac_config_files="$ac_config_files Makefile autotools/gnulib/Makefile"
 
 cat >confcache <<\_ACEOF
diff -ru pax-utils-HEAD.orig/configure.ac pax-utils-HEAD/configure.ac
--- pax-utils-HEAD.orig/configure.ac	2017-04-18 16:25:48.000000000 +0200
+++ pax-utils-HEAD/configure.ac	2017-04-18 16:27:11.000000000 +0200
#@@ -62,6 +62,8 @@
 	AX_CHECK_COMPILE_FLAG(flag, AS_VAR_APPEND([CFLAGS], " flag"))
 ])
 
+AC_CHECK_HEADERS([linux/securebits.h])
+
 AC_CONFIG_FILES([
 	Makefile
 	autotools/gnulib/Makefile
diff -ru pax-utils-HEAD.orig/porting.h pax-utils-HEAD/porting.h
--- pax-utils-HEAD.orig/porting.h	2017-03-03 21:07:15.000000000 +0100
+++ pax-utils-HEAD/porting.h	2017-04-18 16:18:22.000000000 +0200
@@ -46,7 +46,9 @@
 #endif
 #if defined(__linux__)
 # include <sys/prctl.h>
-# include <linux/securebits.h>
+# if !defined(HAVE_CONFIG_H) || defined(HAVE_LINUX_SECUREBITS_H)
+#  include <linux/securebits.h>
+# endif
 #endif
 #if defined(__GLIBC__) || defined(__UCLIBC__) || defined(__ANDROID__)
 # include <byteswap.h>