[CMake] Set the default ABI version for Fuchsia in CMake as well

This is neeeded since the CMake value is used for the SOVERSION.

Differential Revision: https://reviews.llvm.org/D45529

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@329983 91177308-0d34-0410-b5e6-96231b3b80d8

CMakeLists.txt

@@ -97,7 +97,12 @@ option(LIBCXX_INSTALL_SUPPORT_HEADERS "Install libc++ support headers." ON)
 cmake_dependent_option(LIBCXX_INSTALL_EXPERIMENTAL_LIBRARY
         "Install libc++experimental.a" ON
         "LIBCXX_ENABLE_EXPERIMENTAL_LIBRARY;LIBCXX_INSTALL_LIBRARY" OFF)
-set(LIBCXX_ABI_VERSION 1 CACHE STRING "ABI version of libc++.")
+if (FUCHSIA)
+  set(DEFAULT_ABI_VERSION 2)
+else()
+  set(DEFAULT_ABI_VERSION 1)
+endif()
+set(LIBCXX_ABI_VERSION ${DEFAULT_ABI_VERSION} CACHE STRING "ABI version of libc++.")
 option(LIBCXX_ABI_UNSTABLE "Unstable ABI of libc++." OFF)
 option(LIBCXX_ABI_FORCE_ITANIUM "Ignore auto-detection and force use of the Itanium ABI.")
 option(LIBCXX_ABI_FORCE_MICROSOFT "Ignore auto-detection and force use of the Microsoft ABI.")
@@ -619,7 +624,7 @@ if (LIBCXX_STANDALONE_BUILD)
 endif()
 
 # Configuration file flags =====================================================
-if (NOT LIBCXX_ABI_VERSION EQUAL "1")
+if (NOT LIBCXX_ABI_VERSION EQUAL DEFAULT_ABI_VERSION)
   config_define(${LIBCXX_ABI_VERSION} _LIBCPP_ABI_VERSION)
 endif()
 config_define_if(LIBCXX_ABI_UNSTABLE _LIBCPP_ABI_UNSTABLE)