[master] 06c4900c4 Document cpio as a build requirement

[Nils Goroll]

commit 06c4900c4a61dbaa652483dd03a17894bdac1598
Author: Nils Goroll <nils.goroll at uplex.de>
Date:   Thu Jun 18 16:03:49 2020 +0200

    Document cpio as a build requirement
    
    note: on SmartOS, it should be part of the base install
    
    Ref #3309

diff --git a/doc/sphinx/installation/install_source.rst b/doc/sphinx/installation/install_source.rst
index 488fe235c..7a7893926 100644
--- a/doc/sphinx/installation/install_source.rst
+++ b/doc/sphinx/installation/install_source.rst
@@ -26,6 +26,8 @@ you can either::
 
 	pkg install automake pkgconf py36-sphinx py36-docutils pcre libtool
 
+.. XXX does cpio need to be installed on FreeBSD?
+
 And optionally, to be able to run all the testcases::
 
 	pkg install haproxy nghttp2 vttest
@@ -55,7 +57,8 @@ them (replace ``sudo apt-get install`` if needed)::
 	libtool \
 	pkg-config \
 	python3-docutils \
-	python3-sphinx
+	python3-sphinx \
+	cpio
 
 Optionally, to rebuild the svg files::
 
@@ -104,7 +107,8 @@ packages::
 	ncurses-devel \
 	pcre-devel \
 	pkgconfig \
-	python3-docutils
+	python3-docutils \
+	cpio
 
 Optionally, to rebuild the svg files::