[PATCH] [libcxxabi] Add support for building and testing the unwinder.

[Dan Albert]

================
Comment at: src/Unwind/CMakeLists.txt:65
@@ +64,3 @@
+append_if(link_flags LIBCXXABI_HAS_NODEFAULTLIBS_FLAG -nodefaultlibs)
+
+if ( APPLE )
----------------
Jon Roelofs wrote:
> lib/buildit has a big list of EXTRA_FLAGS. Are those taken care of here?
> 
> >    EXTRA_FLAGS="-fstrict-aliasing -Wstrict-aliasing=2 \
> >      -Wsign-conversion -Wshadow -Wconversion -Wunused-variable \
> >      -Wmissing-field-initializers -Wchar-subscripts -Wmismatched-tags \
> >      -Wmissing-braces -Wshorten-64-to-32 -Wsign-compare \
> >      -Wstrict-aliasing=2 -Wstrict-overflow=4 -Wunused-parameter \
> >      -Wnewline-eof"
Fixed these in a separate patch since they should have been there regardless of this one. Committed as r212768.

http://reviews.llvm.org/D4448