Install the daemon in libexecdir

I know Debian doesn't use libexecdir, but most other distros do. On Fedora it's
really strange to see a binary in /usr/libexec/fwupd/fwupd and supporting this
not-quite-servicedir is causing confusion in the Makefiles and also problems in
other external tools.

Simply redefine libexecdir if you need the daemon binary to be installed
somewhere different.

contrib/fwupd.spec.in

@@ -143,8 +143,7 @@ make check VERBOSE=1
 %doc README.md AUTHORS NEWS
 %license COPYING
 %config(noreplace)%{_sysconfdir}/fwupd.conf
-%dir %{_libexecdir}/fwupd
+%{_libexecdir}/fwupd
-%{_libexecdir}/fwupd/fwupd
 %{_bindir}/fwupdmgr
 %{_sysconfdir}/pki/fwupd
 %{_sysconfdir}/pki/fwupd-metadata

data/Makefile.am

@@ -17,7 +17,7 @@ $(dbusservicemain_DATA): $(dbusservicemain_in_files) Makefile
 	sed -e "s|\@daemon_user\@|$(daemon_user)|" > $@
 
 %.service: %.service.in Makefile
-	$(AM_V_GEN)sed -e 's|\@servicedir\@|$(libexecdir)|' \
+	$(AM_V_GEN)sed -e 's|\@libexecdir\@|$(libexecdir)|' \
 	               -e 's|\@localstatedir\@|$(localstatedir)|' \
 	               -e 's|\@bootdir\@|$(bootdir)|' \
 	               -e 's|\@bindir\@|$(bindir)|' \

data/fwupd.service.in

@@ -7,7 +7,7 @@ Before=gdm.service
 [Service]
 Type=dbus
 BusName=org.freedesktop.fwupd
-ExecStart=@servicedir@/fwupd/fwupd
+ExecStart=@libexec@/fwupd
 MemoryDenyWriteExecute=yes
 PrivateTmp=yes
 ProtectControlGroups=yes

data/org.freedesktop.fwupd.service.in

@@ -1,6 +1,6 @@
 [D-BUS Service]
 Name=org.freedesktop.fwupd
 Documentation=http://www.fwupd.org/
-Exec=@servicedir@/fwupd/fwupd
+Exec=@libexecdir@/fwupd
 User=root
 SystemdService=fwupd.service