move daemons to libexec

Per the organization anti-pattern, executables are expected to be
installed into libexec instead of bin[1].  Update service files and
meson to install there.

[1]: https://github.com/openbmc/docs/blob/master/anti-patterns.md#incorrect-placement-of-executables-in-sbin-usrsbin-or-bin-usrbin

Change-Id: Ibb102f387c27593c81f41aa0adc3b994ca9185e2
Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
diff --git a/phosphor-virtual-sensor.service.in b/phosphor-virtual-sensor.service.in
index ad4007c..f6c7fc2 100644
--- a/phosphor-virtual-sensor.service.in
+++ b/phosphor-virtual-sensor.service.in
@@ -3,7 +3,7 @@
 
 [Service]
 Restart=always
-ExecStart=@bindir@/virtual-sensor
+ExecStart=@libexecdir@/phosphor-virtual-sensor/virtual-sensor
 Type=dbus
 BusName=xyz.openbmc_project.VirtualSensor
 SyslogIdentifier=phosphor-virtual-sensor