mpm: fixed cmake macro for enabling modules

The macro MPM_REGISTER_COMPONENT did not work as described: in case
the default enable was set to ON and all dependencies were met, the
module was still not enabled.

Also made the status prints more helpful:
- print the default value,
- print the user override (if one was provided)
- print the resulting VAR = VALUE
- print the override hint only if the user did not
  already specify an override

Example of old incorrect behavior:
-- Configuring Mykonos support...
--   Dependency ENABLE_LIBMPM = ON
--   Disabling Mykonos support.
--   Override with -DENABLE_MYKONOS=ON/OFF

Example of new correct behavior (also with changed prints):
-- Configuring Mykonos support...
--   Default value ENABLE_MYKONOS = ON
--   Dependency ENABLE_LIBMPM = ON
--   Enabling Mykonos support (ENABLE_MYKONOS = ON)
--   Override with -DENABLE_MYKONOS=ON/OFF

0 files changed, 0 insertions, 0 deletions