In the page of the manual: 
function.mcrypt-module-get-algo-supported-key-sizes.html

in the title appears:
"mcrypt_module_get_algo_supported_key_sizes"

and in the other hand, just below of "Description" appears:
array mcrypt_module_enc_get_algo_supported_key_sizes (string
algorithm [, string lib_dir])

and it should be
array mcrypt_module_get_algo_supported_key_sizes (string
algorithm [, string lib_dir])

Thanks.
Francis. V. Romera