Bug 663597 - Memory leaks in normalization code
    
    The DN normalization code uses a Slapi_Attr on the stack to avoid
    allocation of the struct.  The contents of the Slapi_Attr are
    never freed.  This patch ensure that the struct is cleared out
    properly.
    
    There was also a leak in the syntax normalization code where a
    pointer to recently allocated string could get overwritten without
    freeing the string first.  This patch frees the string first.
    (cherry picked from commit 4da627a74d756ab627863de6f52dc663d58fb2d2)