Remove LLVM_ENABLE_LIBCXXABI

[Hahnfeld]

Summary

libc++.so is now a linker script that includes -lc++abi if necessary.

[EricWF]

LGTM. Hopefully everybody who used this option now uses linker scripts.

CMakeLists.txt

if(${CMAKE_SYSTEM_NAME} MATCHES "Darwin")
   option(LLVM_ENABLE_MODULE_DEBUGGING "Compile with -gmodules." ON)
   option(LLVM_ENABLE_LOCAL_SUBMODULE_VISIBILITY "Compile with -fmodules-local-submodule-visibility." OFF)
 else()
   option(LLVM_ENABLE_MODULE_DEBUGGING "Compile with -gmodules." OFF)
   option(LLVM_ENABLE_LOCAL_SUBMODULE_VISIBILITY "Compile with -fmodules-local-submodule-visibility." ON)
 endif()
 option(LLVM_ENABLE_CXX1Y "Compile with C++1y enabled." OFF)
 option(LLVM_ENABLE_LIBCXX "Use libc++ if available." OFF)
-option(LLVM_ENABLE_LIBCXXABI "Use libc++abi when using libc++." OFF)
 option(LLVM_ENABLE_PEDANTIC "Compile with pedantic enabled." ON)
 option(LLVM_ENABLE_WERROR "Fail and stop if a warning is triggered." OFF)
 
 if( NOT uppercase_CMAKE_BUILD_TYPE STREQUAL "DEBUG" )
   option(LLVM_ENABLE_ASSERTIONS "Enable assertions" OFF)
 else()
   option(LLVM_ENABLE_ASSERTIONS "Enable assertions" ON)
 endif()

cmake/modules/HandleLLVMStdlib.cmake

if(NOT DEFINED LLVM_STDLIB_HANDLED)
   include(CheckCXXCompilerFlag)
   if(LLVM_ENABLE_LIBCXX)
     if(LLVM_COMPILER_IS_GCC_COMPATIBLE)
       check_cxx_compiler_flag("-stdlib=libc++" CXX_SUPPORTS_STDLIB)
       if(CXX_SUPPORTS_STDLIB)
         append("-stdlib=libc++"
           CMAKE_CXX_FLAGS CMAKE_EXE_LINKER_FLAGS CMAKE_SHARED_LINKER_FLAGS
           CMAKE_MODULE_LINKER_FLAGS)
-        if(LLVM_ENABLE_LIBCXXABI)
-          append("-lc++abi"
-            CMAKE_EXE_LINKER_FLAGS CMAKE_SHARED_LINKER_FLAGS
-            CMAKE_MODULE_LINKER_FLAGS)
-        endif()
       else()
         message(WARNING "Can't specify libc++ with '-stdlib='")
       endif()
     else()
       message(WARNING "Not sure how to specify libc++ for this compiler")
     endif()
   endif()
 endif()