[CMake][libcxx] Use check_c_compiler_flag to check for nodefaultlibs
[CMake][libcxx] Use check_c_compiler_flag to check for nodefaultlibs

We're using -nodefaultlibs to avoid the dependency on C++ library
when using check_cxx_compiler_flag, and as such we cannot use
check_cxx_compiler_flag to check the availability of -nodefaultlibs
itself.

git-svn-id: 756ef344af921d95d562d9e9f9389127a89a6314@299711 91177308-0d34-0410-b5e6-96231b3b80d8

llvm-mirror/libcxx,llvm-mirror/libcxx,llvm-mirror/libcxx,llvm-mirror/libcxx,llvm-mirror/libcxx