ntdll: Fix time units for SystemPerformanceProcessorInformation, and steal idle time for kernel time.

msi: Assume a file is present if the target exists with the same size and there's no file version or hash to verify.

This is needed because the target path can still change after CostFinalize
is executed. This happens in the .NET 1.1 Service Pack 1 installer where a
custom action calls SetTargetPath.

winedbg: Fix 'break file : lineno' command so that file can be in other modules than the current one.