Makefile: Install qemu-img and qemu-nbd man pages only if built

When splitting openSUSE's qemu and qemu-linux-user packages we noticed
that for linux-user-only builds unrelated man pages got installed.
It's surely possible to delete them before packaging, but not installing
them in the first place seems more logical.

Cc: qemu-stable@nongnu.org
Signed-off-by: Andreas Färber <afaerber@suse.de>
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>

Makefile

@@ -306,10 +306,13 @@ install-doc: $(DOCS)
 	$(INSTALL_DATA) QMP/qmp-commands.txt "$(DESTDIR)$(qemu_docdir)"
 ifdef CONFIG_POSIX
 	$(INSTALL_DIR) "$(DESTDIR)$(mandir)/man1"
-	$(INSTALL_DATA) qemu.1 qemu-img.1 "$(DESTDIR)$(mandir)/man1"
+	$(INSTALL_DATA) qemu.1 "$(DESTDIR)$(mandir)/man1"
+ifneq ($(TOOLS),)
+	$(INSTALL_DATA) qemu-img.1 "$(DESTDIR)$(mandir)/man1"
 	$(INSTALL_DIR) "$(DESTDIR)$(mandir)/man8"
 	$(INSTALL_DATA) qemu-nbd.8 "$(DESTDIR)$(mandir)/man8"
 endif
+endif
 ifdef CONFIG_VIRTFS
 	$(INSTALL_DIR) "$(DESTDIR)$(mandir)/man1"
 	$(INSTALL_DATA) fsdev/virtfs-proxy-helper.1 "$(DESTDIR)$(mandir)/man1"