Const Tracing

[goto-bus-stop]

Zetnus showed a script like this:

if UP_EXTENSION #define RND_AVAILABLE
elseif DE_AVAILABLE #define RND_AVAILABLE
endif

if ALLOW_FULL_RANDOM_PLACEMENT
    if RND_AVAILABLE    /* a check for direct-placement support */
        start_random
            percent_chance 10    #define USE_FULL_RANDOM_PLACEMENT     
        end_random
    endif
endif

if USE_FULL_RANDOM_PLACEMENT
    direct_placement
endif

rms-check flags this as a potential compatibility issue. However, USE_FULL_RANDOM_PLACEMENT will only ever be defined if UP_EXTENSION or DE_AVAILABLE is defined, so this is actually fine. We could do dependency tracing of const definitions to account for this.