libc++: Install headers in include/, rather than lib/

When using the configure build system, the libc++ headers were being
installed in lib/, whereas cmake installs them in include/. Since
include/ makes more sense for headers, we'll make both systems install
headers there.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@194833 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed