debuggerd_handler: implement missing fallback functionality.

Allow the fallback implementation to dump traces and create tombstones
in seccomped processes.

Bug: http://b/35858739
Test: debuggerd -b `pidof media.codec`; killall -ABRT media.codec
Change-Id: I381b283de39a66d8900f1c320d32497d6f2b4ec4
diff --git a/debuggerd/libdebuggerd/tombstone.cpp b/debuggerd/libdebuggerd/tombstone.cpp
index 4686bfd..c05ccc3 100644
--- a/debuggerd/libdebuggerd/tombstone.cpp
+++ b/debuggerd/libdebuggerd/tombstone.cpp
@@ -751,8 +751,11 @@
   dump_crash(&log, map, open_files, pid, tid, siblings, abort_msg_address);
 }
 
-void engrave_tombstone_ucontext(int tombstone_fd, pid_t pid, pid_t tid, uintptr_t abort_msg_address,
-                                siginfo_t* siginfo, ucontext_t* ucontext) {
+void engrave_tombstone_ucontext(int tombstone_fd, uintptr_t abort_msg_address, siginfo_t* siginfo,
+                                ucontext_t* ucontext) {
+  pid_t pid = getpid();
+  pid_t tid = gettid();
+
   log_t log;
   log.current_tid = tid;
   log.crashed_tid = tid;