emacs-28 db259d8fd3: Build Seccomp filter only if we have a 64-bit userspace (Bug#56549)

[Philipp Stephani]

branch: emacs-28
commit db259d8fd369e6036df782d5fe51723a68220074
Author: Philipp Stephani <phst@google.com>
Commit: Philipp Stephani <phst@google.com>

    Build Seccomp filter only if we have a 64-bit userspace (Bug#56549)
    
    * configure.ac (SIZEOF_LONG): New variable.
    * lib-src/Makefile.in (SIZEOF_LONG): New variable; added conditional.
---
 configure.ac        | 4 ++++
 lib-src/Makefile.in | 3 +++
 2 files changed, 7 insertions(+)

diff --git a/configure.ac b/configure.ac
index 312243a41c..741a1a31df 100644
--- a/configure.ac
+++ b/configure.ac
@@ -4380,6 +4380,10 @@ AC_SUBST([HAVE_LIBSECCOMP])
 AC_SUBST([LIBSECCOMP_LIBS])
 AC_SUBST([LIBSECCOMP_CFLAGS])
 
+AC_CHECK_SIZEOF([long])
+SIZEOF_LONG="$ac_cv_sizeof_long"
+AC_SUBST([SIZEOF_LONG])
+
 OLD_LIBS=$LIBS
 LIBS="$LIB_PTHREAD $LIB_MATH $LIBS"
 AC_CHECK_FUNCS(accept4 fchdir gethostname \
diff --git a/lib-src/Makefile.in b/lib-src/Makefile.in
index 338ba0d576..92487edce7 100644
--- a/lib-src/Makefile.in
+++ b/lib-src/Makefile.in
@@ -196,11 +196,13 @@ HAVE_SECCOMP=@HAVE_SECCOMP@
 HAVE_LIBSECCOMP=@HAVE_LIBSECCOMP@
 LIBSECCOMP_LIBS=@LIBSECCOMP_LIBS@
 LIBSECCOMP_CFLAGS=@LIBSECCOMP_CFLAGS@
+SIZEOF_LONG=@SIZEOF_LONG@
 
 # Currently, we can only generate seccomp filter files for x86-64.
 ifeq ($(HAVE_SECCOMP),yes)
 ifeq ($(HAVE_LIBSECCOMP),yes)
 ifeq ($(shell uname -m),x86_64)
+ifeq ($(SIZEOF_LONG),8)
 # We require SECCOMP_RET_KILL_PROCESS, which is only available in
 # Linux 4.14 and later.
 ifeq ($(shell { echo 4.14; uname -r | cut -d . -f 1-2; } | \
@@ -211,6 +213,7 @@ endif
 endif
 endif
 endif
+endif
 
 ifeq ($(SECCOMP_FILTER),1)
 DONT_INSTALL += seccomp-filter$(EXEEXT)