Squashed 'third_party/abseil/' content from commit ddf8e52a2

Change-Id: I330cdc687395c6605ad027b855e313ff4a2059e9
git-subtree-dir: third_party/abseil
git-subtree-split: ddf8e52a2918dd0ccec75d3e2426125fa3926724
diff --git a/absl/debugging/internal/stacktrace_unimplemented-inl.inc b/absl/debugging/internal/stacktrace_unimplemented-inl.inc
new file mode 100644
index 0000000..e256fdd
--- /dev/null
+++ b/absl/debugging/internal/stacktrace_unimplemented-inl.inc
@@ -0,0 +1,22 @@
+#ifndef ABSL_DEBUGGING_INTERNAL_STACKTRACE_UNIMPLEMENTED_INL_H_
+#define ABSL_DEBUGGING_INTERNAL_STACKTRACE_UNIMPLEMENTED_INL_H_
+
+template <bool IS_STACK_FRAMES, bool IS_WITH_CONTEXT>
+static int UnwindImpl(void** /* result */, int* /* sizes */,
+                      int /* max_depth */, int /* skip_count */,
+                      const void* /* ucp */, int *min_dropped_frames) {
+  if (min_dropped_frames != nullptr) {
+    *min_dropped_frames = 0;
+  }
+  return 0;
+}
+
+namespace absl {
+namespace debugging_internal {
+bool StackTraceWorksForTest() {
+  return false;
+}
+}  // namespace debugging_internal
+}  // namespace absl
+
+#endif  // ABSL_DEBUGGING_INTERNAL_STACKTRACE_UNIMPLEMENTED_INL_H_