Makefile: Use $(BIN) and $(MANPAGES) variable to simplify several targets

There are several places which explicitly list the various generated
binaries, even though a $(BIN) variable already lists them.  There are
several more places that list all the manpage files, introduce a
$(MANPAGES) variable to remove that repetition as well.

Tweak the generation of pasta.1 as a link to passt.1 so it's not just made
as a side effect of the pasta target.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
[sbrivio: add passt.1 and qrap.1 to guest files for distro tests]
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>

test/distro/debian

@@ -39,7 +39,7 @@ endef
 hostb	./passt -P __PIDFILE__ &
 sleep	1
 host	echo
-hout	GUEST_FILES ls -1 *.c *.h *.sh Makefile | tr '\n' ' '; echo
+hout	GUEST_FILES ls -1 *.c *.h *.sh passt.1 qrap.1 Makefile | tr '\n' ' '; echo
 
 
 test	Debian GNU/Linux 8 (jessie), amd64

test/distro/fedora

@@ -60,7 +60,7 @@ hostb	./passt -P __PIDFILE__ &
 sleep	1
 host	echo
 hout	DNS6 sed -n 's/^nameserver \([^:]*:\)\([^%]*\).*/\1\2/p' /etc/resolv.conf | head -1
-hout	GUEST_FILES ls -1 *.c *.h *.sh Makefile | tr '\n' ' '; echo
+hout	GUEST_FILES ls -1 *.c *.h *.sh passt.1 qrap.1 Makefile | tr '\n' ' '; echo
 
 
 test	Fedora 26, x86_64

test/distro/opensuse

@@ -39,7 +39,7 @@ hostb	./passt -P __PIDFILE__ &
 sleep	1
 host	echo
 hout	DNS6 sed -n 's/^nameserver \([^:]*:\)\([^%]*\).*/\1\2/p' /etc/resolv.conf | head -1
-hout	GUEST_FILES ls -1 *.c *.h *.sh Makefile | tr '\n' ' '; echo
+hout	GUEST_FILES ls -1 *.c *.h *.sh passt.1 qrap.1 Makefile | tr '\n' ' '; echo
 
 
 test	OpenSUSE Leap 15.1

test/distro/ubuntu

@@ -38,7 +38,7 @@ endef
 hostb	./passt -P __PIDFILE__ &
 sleep	1
 host	echo
-hout	GUEST_FILES ls -1 *.c *.h *.sh Makefile | tr '\n' ' '; echo
+hout	GUEST_FILES ls -1 *.c *.h *.sh passt.1 qrap.1 Makefile | tr '\n' ' '; echo
 
 
 test	Ubuntu 14.04.5 LTS (Trusty Tahr), amd64