This is consistent with other similar expressions such as PLATFORM_ID,
and makes the CONFIGURATION expression obsolete.
Fix an off-by-one error in
GeneratorExpressionContent::EvaluateParameters exposed by a unit test.
Remove the test for 'bad' nullary use of $<CONFIG>.
Add a unit test to verify that $<CONFIG> and $<CONFIGURATION> have
the same value.
3917d86b26