Fix android arm64 prebuild by disabling exceptions

[vweevers]

Problem: loading the android-arm64 prebuild failed with "cannot locate symbol _Unwind_Resume". Likely because that symbol does not exist (or is hidden) on some android devices. I could not positively confirm that because I could not get gdb or lldb to work in termux. Luckily we don't have to, because _Unwind_Resume is a function used for exceptions, which we don't need AFAICT.

Solution: disable exceptions, on both our code and leveldb code.

Closes #705.

@christianbundy, /cc @staltz as the author of #411 which enabled exceptions.

[vweevers]

I ran npm t as well as npm run test-gc in termux, with a prebuild and built from source, all pass.

[vweevers]

5.5.1 (published shortly after 5.5.0, for which I had already pushed git tags but I couldn't publish yet).