Make ada_catchpoint_location's owner ctor parameter be ada_catchpoint

This commit changes ada_catchpoint_location's ctor from:

  ada_catchpoint_location (breakpoint *owner)

to:

  ada_catchpoint_location (ada_catchpoint *owner)

just to make the code better document intention.

To do this, we need to move the ada_catchpoint_location type's
definition to after ada_catchpoint is defined, otherwise the compiler
doesn't know that ada_catchpoint is convertible to struct breakpoint.

Change-Id: Id908b2e38bde30b262381e00c5637adb9bf0129d