[vm] Fail to build with `-Werror=format-security` enabled

[otavio]

Using -Werror=format-security on GCC to increase security on the generated code, the build fails.

For reference: https://fedoraproject.org/wiki/Format-Security-FAQ

[ItaloYeltsin]

We have a lot of warnings to solve in order to make this build possible using such a flag. For example, for iOS, the number of warnings is about 460.

[otavio]

Yeah, we disabled it for now but those warnings are real issues and it'd be good to eventually fix them.

[acmlira]

In the next few days we will be working on things nearby (#71) we can resume this discussion.