Try to handle changing names for journal packages

When checking if we have the development files for libsystemd's journal
APIs, check for either 'libsystemd >= 209' and 'libsystemd-journal'.  If
we find 'libsystemd', define the 'journald' tag, which defaults to using
the 'libsystemd.pc' file.  If we find the older 'libsystemd-journal',
define both the 'journald' and 'journald_compat' tags, which causes the
'libsystemd-journal.pc' file to be consulted instead.

Signed-off-by: Nalin Dahyabhai <nalin@redhat.com> (github: nalind)

daemon/logger/journald/read.go

@@ -2,7 +2,6 @@
 
 package journald
 
-// #cgo pkg-config: libsystemd-journal
 // #include <sys/types.h>
 // #include <sys/poll.h>
 // #include <systemd/sd-journal.h>

daemon/logger/journald/read_native.go

@@ -0,0 +1,6 @@
+// +build linux,cgo,!static_build,journald,!journald_compat
+
+package journald
+
+// #cgo pkg-config: libsystemd
+import "C"

daemon/logger/journald/read_native_compat.go

@@ -0,0 +1,6 @@
+// +build linux,cgo,!static_build,journald,journald_compat
+
+package journald
+
+// #cgo pkg-config: libsystemd-journal
+import "C"

hack/make.sh

@@ -118,8 +118,10 @@ fi
 
 if [ -z "$DOCKER_CLIENTONLY" ]; then
 	DOCKER_BUILDTAGS+=" daemon"
-	if pkg-config libsystemd-journal 2> /dev/null ; then
+	if pkg-config 'libsystemd >= 209' 2> /dev/null ; then
 		DOCKER_BUILDTAGS+=" journald"
+	elif pkg-config 'libsystemd-journal' 2> /dev/null ; then
+		DOCKER_BUILDTAGS+=" journald journald_compat"
 	fi
 fi