RuntimeLibcalls: Read exception model from the module flag (#223971)
Source the exception model in the RuntimeLibcallsInfo(Module)
constructor from the "exception-model" module flag via
Module::getExceptionModel(), instead of forwarding it from TargetOptions.
An absent flag resolves to Default and then to the triple default; an explicit "none"
disables exceptions.
Since the model now comes from the module, drop the ExceptionModel that
RuntimeLibraryAnalysis carried and forwarded, and its argument at every
construction site.
Co-authored-by: Claude (Claude-Opus-4.8) <noreply@anthropic.com>