Install nscd for caching LDAP queries

nscd is recommended package for libpam-ldapd and libnss-ldapd, but
since we disabled Install-Recommends for apt in
https://gerrit.mcp.mirantis.net/14431 we need to specify this package in
linux formula.
nscd is a daemon which handles passwd, group and host lookups for
running programs and caches the results for the next query.

Change-Id: Ia17441da2b3072d943d0e9225721dc9921de2514

linux/map.jinja

 {% set ldap = salt['grains.filter_by']({
     'RedHat': {
         'enabled': false,
-        'pkgs': ['openldap-clients', 'nss-pam-ldapd', 'authconfig'],
+        'pkgs': ['openldap-clients', 'nss-pam-ldapd', 'authconfig', 'nscd'],
         'version': '3',
         'scope': 'sub',
         'uid': 'nslcd',
     },
     'Debian': {
         'enabled': false,
-        'pkgs': ['libnss-ldapd', 'libpam-ldapd'],
+        'pkgs': ['libnss-ldapd', 'libpam-ldapd', 'nscd'],
         'version': '3',
         'scope': 'sub',
         'uid': 'nslcd',