[libc++] Remove install_name and compatibility_version on OS X

CMake already specifies those, and we never actually want those to be
used. In fact, r357811 re-ordered those flags in a way that the
explicitly-provided install_name was overriding the CMake-provided
install_name (instead of the other way around). This caused the dylib
to be considered a system dylib, and hence the explicitly provided rpath
to be ignored. This, in turn, caused some unit tests to start linking
against the system libc++.dylib instead of the freshly-built one.
Specifically, the unit tests that started linking against the system
dylib are those that didn't specify a DYLD_LIBRARY_PATH, such as
last_write_time.sh.cpp.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@357946 91177308-0d34-0410-b5e6-96231b3b80d8

lib/CMakeLists.txt

@@ -198,8 +198,6 @@ if (LIBCXX_ENABLE_SHARED)
       set(RE_EXPORT_LIST "${CMAKE_CURRENT_SOURCE_DIR}/libc++abi.v${LIBCXX_LIBCPPABI_VERSION}.exp")
     endif()
     target_link_libraries(cxx_shared PRIVATE
-      "-compatibility_version 1"
-      "-install_name /usr/lib/libc++.1.dylib"
       "-Wl,-unexported_symbols_list,${CMAKE_CURRENT_SOURCE_DIR}/libc++unexp.exp"
       "-Wl,-reexported_symbols_list,${RE_EXPORT_LIST}"
       "-Wl,-force_symbols_not_weak_list,${CMAKE_CURRENT_SOURCE_DIR}/notweak.exp"