[libc++] Fix the CMake build on Mac when setting MACOSX_DEPLOYMENT_TARGET=10.6

The build file was trying to use LIBCXX_VERSION, which isn't set
anywhere, and also forgot to split the 'compile_flags' list.

Differential Revision: http://reviews.llvm.org/D4860

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@215463 91177308-0d34-0410-b5e6-96231b3b80d8

lib/CMakeLists.txt

@@ -54,7 +54,7 @@ if ( APPLE )
     list(APPEND compile_flags "-U__STRICT_ANSI__")
     list(APPEND link_flags
       "-compatibility_version 1"
-      "-current_version ${LIBCXX_VERSION}"
+      "-current_version 1"
       "-install_name /usr/lib/libc++.1.dylib"
       "-Wl,-reexport_library,/usr/lib/libc++abi.dylib"
       "-Wl,-unexported_symbols_list,${CMAKE_CURRENT_SOURCE_DIR}/libc++unexp.exp"
@@ -84,6 +84,7 @@ if ( APPLE )
   endif()
 endif()
 
+string(REPLACE ";" " " compile_flags "${compile_flags}")
 string(REPLACE ";" " " link_flags "${link_flags}")
 
 set_target_properties(cxx