[libcxxabi] Refactor building and testing libc++abi without threads

Summary:
This patch adds CMake support for building and testing libc++abi without threads. 


1. Add `LIBCXXABI_ENABLE_THREADS` option to CMake.
2. Propagate `LIBCXXABI_ENABLE_THREADS` to lit via lit.site.cfg.in
3. Configure tests for `LIBCXXABI_ENABLE_THREADS=OFF

Currently the test suite does not work when libc++abi is built without threads because that information does not propagate to the test suite.



Reviewers: danalbert, mclow.lists, jroelofs

Reviewed By: jroelofs

Subscribers: cfe-commits

Differential Revision: http://reviews.llvm.org/D6393

llvm-svn: 222702

1 files changed, 4 insertions, 1 deletions

diff --git a/libcxxabi/test/test_exception_storage.cpp b/libcxxabi/test/test_exception_storage.cpp
index f1e2fb5e477..0d5deaa3735 100644
--- a/libcxxabi/test/test_exception_storage.cpp
+++ b/libcxxabi/test/test_exception_storage.cpp
@@ -56,7 +56,10 @@ int main ( int argc, char *argv [] ) {
 
 #if LIBCXXABI_HAS_NO_THREADS
     size_t thread_globals;
-    retVal = thread_code(&thread_globals) != 0;
+    // Check that __cxa_get_globals() is not NULL.
+    if (thread_code(&thread_globals) == 0) {
+        retVal = 1;
+    }
 #else
 //  Make the threads, let them run, and wait for them to finish
     for ( int i = 0; i < NUMTHREADS; ++i )