move IPA-related http runtime directories to common subdirectory

When both 'mod_auth_kerb' and 'mod_auth_gssapi' are installed at the same
time, they use common directory for storing Apache ccache file. Uninstallation
of 'mod_auth_kerb' removes this directory leading to invalid CCache path for
httpd and authentication failure.

Using an IPA-specific directory for credential storage during apache runtime
avoids this issue.

https://fedorahosted.org/freeipa/ticket/4973

Reviewed-By: David Kupka <dkupka@redhat.com>

init/systemd/httpd.service

@@ -1,4 +1,4 @@
 .include /usr/lib/systemd/system/httpd.service
 
 [Service]
-Environment=KRB5CCNAME=/var/run/httpd/krbcache/krb5ccache
+Environment=KRB5CCNAME=/var/run/httpd/ipa/krbcache/krb5ccache

init/systemd/ipa.conf.tmpfiles

@@ -1,3 +1,5 @@
 d /var/run/ipa_memcached 0700 apache apache
 d /var/run/ipa 0700 root root
-d /var/run/httpd/clientcaches 0700 apache apache
+d /var/run/httpd/ipa 0700 apache apache
+d /var/run/httpd/ipa/clientcaches 0700 apache apache
+d /var/run/httpd/ipa/krbcache 0700 apache apache