Ticket #48919 - Compiler warnings while building 389-ds-base on RHEL7
Description: Fixing additional covscan errors.
1. RESOURCE_LEAK
ldap/servers/slapd/agtmmap.c
agt_mopen_stats - leaked_handle: Handle variable "fd" going out of scope leaks the handle.
2. CHECKED_RETURN
ldap/servers/slapd/back-ldbm/cache.c
entrycache_return - check_return: Calling "remove_hash" without checking return value
3. NULL_RETURNS
ldap/systools/idsktune.c
linux_check_cpu_features - dereference: Dereferencing a pointer that might be null "cpuinfo" when calling "fclose".
4. UNINIT
ldap/servers/slapd/detach.c
detach - uninit_use: Using uninitialized value "rc".
https://fedorahosted.org/389/ticket/48919
(cherry picked from commit 381caf52a06ad8cefa9daa99586878249a4aa4f2)