Add a helper binary to create a basic Secure Computing filter.scratch/seccomp

The binary uses the 'seccomp' helper library.  The library isn't
needed to load the generated Secure Computing filter.

* configure.ac: Check for 'seccomp' header and library.

* lib-src/seccomp-filter.c: New helper binary to generate a generic
Secure Computing filter for GNU/Linux.

* lib-src/Makefile.in (DONT_INSTALL): Add 'seccomp-filter' helper
binary if possible.
(all): Add Secure Computing filter file if possible.
(seccomp-filter$(EXEEXT)): Compile helper binary.
(seccomp-filter.bpf seccomp-filter.pfc): Generate filter files.

* test/src/emacs-tests.el (emacs-tests/seccomp/allows-stdout)
(emacs-tests/seccomp/forbids-subprocess): New unit tests.

* test/Makefile.in (src/emacs-tests.log): Add dependency on the helper
binary.

1 files changed, 2 insertions, 0 deletions

diff --git a/test/Makefile.in b/test/Makefile.in
index b6cf6493e32..670bdd6c3da 100644
--- a/test/Makefile.in
+++ b/test/Makefile.in
@@ -272,6 +272,8 @@ $(test_module): $(test_module:${SO}=.c) ../src/emacs-module.h
           $(srcdir)/../lib/timespec.c $(srcdir)/../lib/gettime.c
 endif
 
+src/emacs-tests.log: ../lib-src/seccomp-filter.c
+
 ## Check that there is no 'automated' subdirectory, which would
 ## indicate an incomplete merge from an older version of Emacs where
 ## the tests were arranged differently.