Nothing in the Utility or Host layers uses Diagnostics. Its only callers
are Debugger (the always-on log feeder), SBDebugger, and the
SystemInitializerCommon lifecycle. Those all live in Core or above. The
header depends only on Utility primitives (FileSpec, Log, Error), and
lldbInitialization already links lldbCore, so the move adds no new link
dependency anywhere.
Relocating it to Core lets Diagnostics reach Debugger, Target,
CommandInterpreter, and Host, which simplifies an upcoming change that
collect a richer diagnostics bundle (statistics, command snapshots,
invocation, etc) and allows us to implement that directly in the
Diagnostics class.
Jonas Devlieghere
2ceab13545