fix coverity issues with uninit vals, no return checking
    
    12766 Uninitialized pointer read
    In _entryrdn_replace_suffix_id(): Reads an uninitialized pointer or its target
    12765 Uninitialized pointer read
    In txn_test_threadmain(): Reads an uninitialized pointer or its target
    12764 Unchecked return value
    In txn_test_threadmain(): Value returned from a function is not checked for errors before being used
    12763 Unchecked return value
    In entrycache_replace(): Value returned from a function is not checked for errors before being used
    12762 Unchecked return value
    In entrycache_add_int(): Value returned from a function is not checked for errors before being used
    Reviewed by: mreynolds (Thanks!)
    (cherry picked from commit 98784ec829061e969c84b3cd5882326a0376ebd6)