Initial checkin commit for lockfree stack.
Tests not yet included.
diff --git a/BUILD b/BUILD
index da9866d..a375b04 100644
--- a/BUILD
+++ b/BUILD
@@ -47,6 +47,7 @@
     "src/core/support/env.h",
     "src/core/support/file.h",
     "src/core/support/murmur_hash.h",
+    "src/core/support/stack_lockfree.h",
     "src/core/support/string.h",
     "src/core/support/string_win32.h",
     "src/core/support/thd_internal.h",
@@ -73,6 +74,7 @@
     "src/core/support/murmur_hash.c",
     "src/core/support/slice.c",
     "src/core/support/slice_buffer.c",
+    "src/core/support/stack_lockfree.c",
     "src/core/support/string.c",
     "src/core/support/string_posix.c",
     "src/core/support/string_win32.c",
@@ -873,6 +875,7 @@
     "src/core/support/murmur_hash.c",
     "src/core/support/slice.c",
     "src/core/support/slice_buffer.c",
+    "src/core/support/stack_lockfree.c",
     "src/core/support/string.c",
     "src/core/support/string_posix.c",
     "src/core/support/string_win32.c",
@@ -920,6 +923,7 @@
     "src/core/support/env.h",
     "src/core/support/file.h",
     "src/core/support/murmur_hash.h",
+    "src/core/support/stack_lockfree.h",
     "src/core/support/string.h",
     "src/core/support/string_win32.h",
     "src/core/support/thd_internal.h",