Add iec559 double definition check

[armallen]

Rationale

We need to check double type definition for ASIL purposes. This adds a simple check, then called by integrity_core_common (or any library needing to check double definition)

Related PRs

swift-nav/cmake#169
https://github.com/swift-nav/orion-engine/pull/7226

[jungleraptor]

I'm a little confused about how this is supposed to work.

I'm actually surprised that the build didn't complain about making a cc_binary a dep of cc_library - that's probably the first warning sign.

In any case this is a runtime failure so I don't see how this will fail the build if the compiler is indeed not compatible.

Can we make this check constexpr instead so that it actually fails at compile time?

[armallen]

I'm a little confused about how this is supposed to work.

I'm actually surprised that the build didn't complain about making a cc_binary a dep of cc_library - that's probably the first warning sign.

In any case this is a runtime failure so I don't see how this will fail the build if the compiler is indeed not compatible.

Can we make this check constexpr instead so that it actually fails at compile time?

🤦 sorry about this, I think we'll go for a static assert in the library instead