[GEN][ZH] Fix USA Supply Drop Zone event triggering instantly when previously subdued while under construction

[Mauller]

• Fixes: USA supply drop zone exploit #374
• Closes: [ZH] Fix Supply drops instantly triggering when built while disabled #423

This PR is an alternate / updated implementation of an earlier orphaned PR

This PR prevents supply drops from instantly triggering when they were being subdued while under construction.
The issue stems from m_nextCreationFrame being incremented while the building is disabled.

If the building is still subdued when transitioning from under construction to constructed, the above occurs before the timer gets inintialised inside the early return within the if( m_nextCreationFrame == 0 ) block.
This results in the shouldCreate() block getting fully triggered and a supply drop being created

This PR also adds the subdual behaviour in a non retail block to the generals variant of the code as it was missing before.

[Caball009]

This fixes the issue but doesn't fix the timer if the building is still subdued when construction finishes. As far as I can tell this is only a visual bug, and as soon as the microwave tank stops the attack, the timer starts to count down from 2 minutes like normal. I don't know what happens if this timer reaches 0.

[Mauller]

This fixes the issue but doesn't fix the timer if the building is still subdued when construction finishes. As far as I can tell this is only a visual bug, and as soon as the microwave tank stops the attack, the timer starts to count down from 2 minutes like normal. I don't know what happens if this timer reaches 0.

It's just a visual glitch, the moment the building is released from being subdued the timer gets initialised properly.

[Caball009]

It's just a visual glitch, the moment the building is released from being subdued the timer gets initialised properly.

There's also a divide by float 0, which is unfortunate. I'm going to check it out. I think it can be avoided.

[Mauller]

Tweaked so the disabling code in generals version is just the fixed code and all behind a non retail compatible include

[Mauller]

Updated with the recent recommendations, works as expected and also prevents some visual and division issues.

[Caball009]

Looks good.

[Mauller]

Fudged spelling in the comments.

[xezon]

Fix looks very correct.

The code comment has long width. Can be beautified.

[Mauller]

Tweaked the code comment a little, condensed it a touch.