Merge #91

91: Add inline-asm build to CI, fix build r=dkhayes117 a=Disasm

https://github.com/rust-embedded/riscv/pull/86

 introduced new `asm!` syntax which is enabled with the `inline-asm` feature. However, it doesn't work with current nightly since `asm_const` unstable feature is not enabled. This PR fixes the problem and adds automatic checks to CI.

Co-authored-by: Vadim Kaushan <admin@disasm.info>