[PATCH] [libcxxabi] Add a cmake build system.

[Dan Albert]

If anyone could test this on msvc I'd appreciate it. My install appears no longer be sane. I'll hack at it more on later...

================
Comment at: CMakeLists.txt:128
@@ +127,3 @@
+
+if (LIBCXXABI_HAS_NOSTDINCXX_FLAG)
+  list(APPEND LIBCXXABI_CXX_REQUIRED_FLAGS -nostdinc++)
----------------
Eric, forgot to address your comment. Will fix that in a moment.

================
Comment at: src/CMakeLists.txt:27
@@ +26,3 @@
+if (LIBCXXABI_LIBCXX_PATH)
+  include_directories("${LIBCXXABI_LIBCXX_PATH}/include")
+elseif (NOT LIBCXXABI_BUILT_STANDALONE)
----------------
Now using include_directories() instead of target_include_directories() so we don't require cmake 2.8.11.

================
Comment at: src/CMakeLists.txt:28
@@ +27,3 @@
+  include_directories("${LIBCXXABI_LIBCXX_PATH}/include")
+elseif (NOT LIBCXXABI_BUILT_STANDALONE)
+  include_directories("${LLVM_MAIN_SRC_DIR}/projects/libcxx/include")
----------------
thakis, you had asked about auto-detecting libc++ if building in tree. It was actually already done, just in src/CMakeLists.txt, not the root one.

http://reviews.llvm.org/D4359