libseccomp: Add version 2.5.1

From the [Web site][1]:

> The libseccomp library provides an easy to use, platform independent,
> interface to the Linux Kernel's syscall filtering mechanism. The
> libseccomp API is designed to abstract away the underlying BPF based
> syscall filter language and present a more conventional function-call
> based filtering interface that should be familiar to, and easily
> adopted by, application developers.

virtiofsd requires libseccomp:

    ../tools/meson.build:12:6: ERROR: Problem encountered: virtiofsd requires libcap-ng-devel and seccomp-devel

[1]: https://github.com/seccomp/libseccomp

libseccomp.be0

@@ -0,0 +1,35 @@
+#!/usr/bin/env beesh
+
+# BEE_VERSION libseccomp-2.5.1-0
+
+SRCURL[0]="https://github.com/seccomp/libseccomp/releases/download/v${PKGVERSION}/libseccomp-${PKGVERSION}.tar.gz"
+
+# PATCHURL+=()
+
+# build_in_sourcedir
+
+# sourcesubdir_append src
+
+#mee_extract() {
+#    bee_extract "${@}"
+#}
+
+#mee_patch() {
+#    bee_patch "${@}"
+#}
+
+#mee_configure() {
+#    bee_configure
+#}
+
+#mee_build() {
+#    bee_build
+#}
+
+#mee_install() {
+#    bee_install
+#}
+
+#mee_install_post() {
+#    exit
+#}