[libc++abi] Default LIBCXXABI_ENABLE_NEW_DELETE_DEFINITIONS to OFF

[tambre]

Summary

Building LLVM now requires GCC 5.1.
A GCC 4.9 bug should no longer be of concern.

[ldionne]

There is a patch for this: https://reviews.llvm.org/D68269

It has some issue, I need to go back and revisit this in light of the changes in the test suite.

[tambre]

Ah, I see. Might be worth updating the comment at least to point to that review.

[ldionne]

In D77298#1957554, @tambre wrote:

Ah, I see. Might be worth updating the comment at least to point to that review.

Done in c3b5c98e39533302d27f13895dad1e7b2e425f68!

libcxxabi/CMakeLists.txt

 option(LIBCXXABI_HAS_PTHREAD_API "Ignore auto-detection and force use of pthread API" OFF)
 option(LIBCXXABI_HAS_EXTERNAL_THREAD_API
   "Build libc++abi with an externalized threading API.
   This option may only be set to ON when LIBCXXABI_ENABLE_THREADS=ON." OFF)
 option(LIBCXXABI_BUILD_EXTERNAL_THREAD_LIBRARY
   "Build libc++abi with an externalized threading library.
    This option may only be set to ON when LIBCXXABI_ENABLE_THREADS=ON" OFF)
 
-# FIXME: This option should default to off. Unfortunatly GCC 4.9 fails to link
-# programs to due undefined references to new/delete in libc++abi. Once this
-# has been fixed or worked around the default value should be changed.
 option(LIBCXXABI_ENABLE_NEW_DELETE_DEFINITIONS
     "Build libc++abi with definitions for operator new/delete. Normally libc++
-    provides these definitions" ON)
+    provides these definitions" OFF)
 option(LIBCXXABI_BUILD_32_BITS "Build 32 bit libc++abi." ${LLVM_BUILD_32_BITS})
 option(LIBCXXABI_INCLUDE_TESTS "Generate build targets for the libc++abi unit tests." ${LLVM_INCLUDE_TESTS})
 set(LIBCXXABI_LIBDIR_SUFFIX "${LLVM_LIBDIR_SUFFIX}" CACHE STRING
     "Define suffix of library directory name (32/64)")
 option(LIBCXXABI_INSTALL_LIBRARY "Install the libc++abi library." ON)
 set(LIBCXXABI_TARGET_TRIPLE "" CACHE STRING "Target triple for cross compiling.")
 set(LIBCXXABI_GCC_TOOLCHAIN "" CACHE PATH "GCC toolchain for cross compiling.")
 set(LIBCXXABI_SYSROOT "" CACHE PATH "Sysroot for cross compiling.")