ecbuild_add_option with REQUIRED_PACKAGES not correctly reflected in project summary

[marcosbento]

What happened?

As follow up to #65, we have found that when ecbuild_add_option is used with REQUIRED_PACKAGES to define project options, the project summary doesn't properly reflect the enabled/disabled options.

1. When using CMakeLists.txt:

cmake_minimum_required( VERSION 3.18.4 FATAL_ERROR )
find_package( ecbuild 3.4 REQUIRED )

project( proja LANGUAGES NONE VERSION 0.2 )
ecbuild_add_option(
    FEATURE MYFEATURE
    DEFAULT ON
)

project( projb LANGUAGES NONE VERSION 0.1 )
ecbuild_add_option(
    FEATURE MYFEATURE
    DEFAULT OFF
)

project( projc LANGUAGES NONE VERSION 0.3 )
ecbuild_add_option(
    FEATURE MYFEATURE
    DEFAULT ON
    REQUIRED_PACKAGES unexistent       
)

ecbuild_print_summary()

the project configuration output shows option MYFEATURE disabled for projc:

-- [proja] (0.2)
-- Feature TESTS enabled
-- Feature PKGCONFIG enabled
-- Feature MYFEATURE enabled
-- ---------------------------------------------------------
-- [projb] (0.1)
-- Feature TESTS enabled
-- Feature PKGCONFIG enabled
-- Feature MYFEATURE enabled
-- ---------------------------------------------------------
-- [projc] (0.3)
-- Feature TESTS enabled
-- Feature PKGCONFIG enabled
-- Could NOT find unexistent (missing: unexistent_DIR)
-- projc FAILED to find OPTIONAL package unexistent
-- Could NOT find package unexistent required for feature MYFEATURE --
-- Feature MYFEATURE was not enabled (also not requested) -- following required packages weren't found: unexistent

while the project summary incorrect reports that MYFEATURE is enabled (✔) for projc:

 * MYFEATURE, proja(✔): '', projb(✔): '', projc(✔): ''

What are the steps to reproduce the bug?

Configure the provided CMakeLists.txt.

Version

3.8.5

Platform (OS and architecture)

Linux/macOS

Relevant log output

No response

Accompanying data

No response

Organisation

ECMWF