This change:
- Adds implementation for atomic_init builtin
- Fixes atomic_exchange_explicit lowering
- Fixes atomic_store_explicit lowering
- Adds a new line char to LLVM_DEBUG messages printed from SPIRVBuiltins.cpp
The AtomicsBuiltinsFloat.ll test comes from the SPIR-V translator and was extended with additional checks.
As I know we use %[[#]] instead of {{%.+}}.