install dirmngr if needed

as of Ubuntu Yakkety, dirmngr is now in a separate
package (see https://bugs.launchpad.net/ubuntu/+source/apt/+bug/1634464)

this patch updates the install script to install
the dirmngr package if it's not installed.

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
(cherry picked from commit f5263c8074c091555592787e32319a6a4f39e650)
Signed-off-by: Victor Vieux <victorvieux@gmail.com>

hack/install.sh

@@ -406,11 +406,17 @@ do_install() {
 				( set -x; $sh_c 'sleep 3; apt-get install -y -q curl ca-certificates' )
 				curl='curl -sSL'
 			fi
-			if [ ! -e /usr/bin/gpg ]; then
+			if ! command -v gpg > /dev/null; then
 				apt_get_update
 				( set -x; $sh_c 'sleep 3; apt-get install -y -q gnupg2 || apt-get install -y -q gnupg' )
 			fi
 
+			# dirmngr is a separate package in ubuntu yakkety; see https://bugs.launchpad.net/ubuntu/+source/apt/+bug/1634464
+			if ! command -v dirmngr > /dev/null; then
+				apt_get_update
+				( set -x; $sh_c 'sleep 3; apt-get install -y -q dirmngr' )
+			fi
+
 			(
 			set -x
 			for key_server in $key_servers ; do