Call for legacy-support testing

[Fred Wright]

The latest legacy-support-devel is an RC for the next release.  Although 
the list of additions and bugfixes is fairly modest, there's been some 
substantial rework of the headers, both to allow full flexibility for SDK 
choice, and to provide the proper __DARWIN_C_LEVEL conditionals matching 
those in the Apple headers.  Its own tests pass on all platforms, 
including in all cases involving CPU-compatible SDKs "not earlier" than 
the target OS, but in view of the extent of the modifications, more 
widespread testing would be a plus.

If no issues are found, this will probably become a release in about a 
week.

Fred Wright