Make amalgamation smaller

[rogerbinns]

The -16 apis only need to be present when ICU extension is enabled.

API_ARMOR only needs to be on in debug builds

We should be able to omit legacy APIs

[rogerbinns]

-16 APIs have to stay in - https://sqlite.org/forum/forumpost/1eac3b2c9c

[rogerbinns]

Using speedtest I see a very small but consistent performance improvement with API_ARMOR. Speedtest is only using the prepare/binding/step/column apis. A plausible explanation is that it helps the optimiser because it knows later in the code that parameters aren't null etc.

For the 1.2MB shared library text segment, API_ARMOR makes it just over 5,000 bytes larger.

Consequently leaving API_ARMOR on.