use a pre-computed key if the OpenSSL version doesn't support generating rsa keys with exponents > 32 bits

3339.   [func]          Allow the maximum supported rsa exponent size to be                        specified: "max-rsa-exponent-size <value>;" [RT #29228]

                        and asyncload_zt. [RT #26100]

                        in controls. [RT #29694]

                        [RT #29514]

3335.	[func]		nslookup: return a nonzero exit code when unable
			to get an answer. [RT #29492]

                        asyncronous load of a zone. [RT #28326]

                        named to not recover if it looses connectivity.
                        [RT #29623]