phosphor-sync-software-manager: move to libexec

Non-user executables are suppose to be installed into libexec[1].

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

Tested:

```
$ meson install -C builddir --destdir /tmp/phosphor-bmc-code-mgmt
$ find /tmp/phosphor-bmc-code-mgmt/ -name phosphor-sync-software-manager
/tmp/phosphor-bmc-code-mgmt/usr/local/libexec/phosphor-bmc-code-mgmt/phosphor-sync-software-manager
```

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: Ib85bbdf919c244f361d7208d988b243c4a8be6a0
diff --git a/bmc/meson.build b/bmc/meson.build
index cf7152b..abe18fb 100644
--- a/bmc/meson.build
+++ b/bmc/meson.build
@@ -165,6 +165,7 @@
         'sync_watch.cpp',
         dependencies: deps,
         install: true,
+        install_dir: get_option('libexecdir') / 'phosphor-code-mgmt',
     )
 
     install_data('synclist', install_dir: get_option('sysconfdir'))
diff --git a/bmc/xyz.openbmc_project.Software.Sync.service.in b/bmc/xyz.openbmc_project.Software.Sync.service.in
index 5feeaa5..d9db2af 100644
--- a/bmc/xyz.openbmc_project.Software.Sync.service.in
+++ b/bmc/xyz.openbmc_project.Software.Sync.service.in
@@ -2,7 +2,7 @@
 Description=Phosphor Sync Manager that syncs files to the alternate BMC chip
 
 [Service]
-ExecStart=/usr/bin/phosphor-sync-software-manager
+ExecStart=/usr/libexec/phosphor-code-mgmt/phosphor-sync-software-manager
 Restart=always
 
 [Install]