add X509_up_ref() documentation

=head1 NAME

X509_new, X509_free - X509 certificate ASN1 allocation functions

X509_new, X509_free, X509_up_ref - X509 certificate ASN1 allocation functions

=head1 SYNOPSIS

 X509 *X509_new(void);

 void X509_free(X509 *a);

 void X509_up_ref(X509 *a);

=head1 DESCRIPTION

The X509 ASN1 allocation routines, allocate and free an

X509 structure, which represents an X509 certificate.

X509_new() allocates and initializes a X509 structure.

X509_new() allocates and initializes a X509 structure with reference count

B<1>.

X509_free() frees up the B<X509> structure B<a>.

If B<a> is NULL nothing is done.

X509_free() decrements the reference count of B<X509> structure B<a> and

frees it up if the reference count is zero. If B<a> is NULL nothing is done.

X509_up_ref() increments the reference count of B<a>.

=head1 NOTES

The function X509_up_ref() if useful if a certificate structure is being

used by several different operations each of which will free it up after

use: this avoids the need to duplicate the entire certificate structure.

=head1 RETURN VALUES

code that can be obtained by L<ERR_get_error(3)>.

Otherwise it returns a pointer to the newly allocated structure.

X509_free() returns no value.

X509_free() and X509_up_ref() do not return a value.

=head1 SEE ALSO