Language feature support for LLVM-based verifiers

[alastairreid]

This issue is to keep track of the status of Rust language/feature support.
It is limited to LLVM-based verifiers because MIR-based verifiers will probably have completely different issues.
Add new problems as they are discovered with links to more detailed issues if they exist

• #[should_panic] support
• #[test] support
• Hybrid crates that include Rust + C code Hybrid crates that combine Rust and C code are not supported #6
• Crates that rely on C library calls Crates that rely on C libraries are not supported #45
• std.env.args std.env.args does not work #21
• Thread support when only one thread is actually used Threads don't work #5
• Thread support when multiple threads are used Threads don't work #5
• Floating point support (see Wrong behavior when use float number #154 about KLEE)
• Dynamically linked Rust libraries Compliation error when verifying programs that use dynamically linked libraries #111
• Embedded assembly language (see KLEE PR)
• Processor specific SIMD intrinsics Deal with processor-specific SIMD intrinsics in LLVM-based verifiers #44
• Processor specific non-SIMD intrinsics