Split storage_raw_read_fixed_disk in two

In order to use storage_raw_read_fixed_disk in
conditional code, split the function in two parts:
- _uncond, which can't be used in a conditional block
- _cond, which is to be used in a conditional block,
  requires the _uncond in order to work
Introduce lvm_use_api{,_cond,_uncond)

These functions allow a domain to use directly the C API
in order to get information about the lvm instances

There functions are introduced here:
- lvm_use_api which can be used directly
- lvm_use_api_cond can be used in a tunable_policy
- lvm_use_api_uncond is required by lvm_use_api_cond
phpfpm: add new booleans

- phpfpm_can_network_connect_http
- phpfpm_can_read_generic_certs
- phpfpm_can_clamav_connect_unix
Collectd: support various modules via booleans

Newly supported modules are:
- entropy
- hddtemp
- lvm
- nut
- process
- users
Introduce openvpn_read_status
Collectd: add support for openvpn module
Collectd: add access to /etc/mtab (etc_runtime_t)
Collectd: add support for turbostat module
Collectd: introduce collectd_read_var_lib
phpfpm: add boolean for reading collectd data