Compile and link core tests with libuv
diff --git a/binding.gyp b/binding.gyp
index 3e63f73..82ab51b 100644
--- a/binding.gyp
+++ b/binding.gyp
@@ -587,6 +587,7 @@
         'src/core/lib/iomgr/combiner.c',
         'src/core/lib/iomgr/endpoint.c',
         'src/core/lib/iomgr/endpoint_pair_posix.c',
+        'src/core/lib/iomgr/endpoint_pair_uv.c',
         'src/core/lib/iomgr/endpoint_pair_windows.c',
         'src/core/lib/iomgr/error.c',
         'src/core/lib/iomgr/ev_epoll_linux.c',