Reorganise ECC code so it can use FIPS module.

Reorganise ECC code so it can use FIPS module.

Move compression, point2oct and oct2point functions into separate files.

Add a flags field to EC_METHOD.

Add a flag EC_FLAGS_DEFAULT_OCT to use the default compession and oct functions
(all existing methods do this). This removes dependencies from EC_METHOD while
keeping original functionality.

Backport from HEAD with minor changes.