just like llvm 3.7
Since commit 183d05a0 in 2012, this is the default. fixes #18000
183d05a0
This obsoletes a backport for rust.
Package changes from 3.6: - CMake exports patch no longer necessary - Cosmetic purity patch fix - Build libc++ with private libc++abi headers visible from sources - Work around bugs in lldb's configure scripts