[CMake][libcxxabi] Use -nodefaultlibs for CMake checks

Since libc++abi is built with -nodefaultlibs, we should be using this
option even for CMake checks to avoid any inconsistency and also to
avoid dependency on a working C++ standard library just for the setting
up the build itself. The implementation is largely similar to the one
used by libc++.

Differential Revision: https://reviews.llvm.org/D31639

llvm-svn: 299797