This preserves backwards compatibility for two hacks in the Darwin
system module map files:
1. The use of 'requires excluded' to make headers non-modular, which
should really be mapped to 'textual' now that we have this feature.
2. Silently removes a bogus cplusplus requirement from IOKit.avc.
Once we start diagnosing missing requirements and headers on
auto-imports these would have broken compatibility with existing Darwin
SDKs.
llvm-svn: 244912
Ben Langmuir