[linux] fix fatal error on user-invoked SIGTRAP

## Purpose
A `SIGTRAP` in the inferior process originating from a user process
other than ds2 is not an error.

## Overview
* Treat `SIGTRAP` with a code <= 0 as non-fatal as long as it originates
from a process other than ds2.
* Leave the fatal error for unrecognized signal codes > 0 or if the
signal originates from the ds2 process.
* Re-enable the lldb test that was failing due to this issue.

## Problem Details
`SIGTRAP` with a code <= 0 indicates it originates from a user process.
It should not be treated as a fatal error if it comes from a process
other than ds2.

## Validation
The re-enabled lldb test now passes consistently locally on Android.

Author: andrurogerz

Sources/Target/Linux/Thread.cpp

@@ -95,9 +95,6 @@ ErrorCode Thread::updateStopInfo(int waitStatus) {
       _stopInfo.reason = StopInfo::kReasonTrap;
     } else if (_stopInfo.signal == SIGTRAP) { // (5)
       switch (si.si_code) {
-      case 0:
-        _stopInfo.reason = StopInfo::kReasonTrap;
-        break;
       case TRAP_HWBKPT:
       case TRAP_TRACE: {
         auto *hwBpm = process()->hardwareBreakpointManager();
@@ -111,7 +108,16 @@ ErrorCode Thread::updateStopInfo(int waitStatus) {
         _stopInfo.reason = StopInfo::kReasonBreakpoint;
         break;
       default:
-        DS2BUG("unknown sigtrap code");
+        if (si.si_code > 0 || si.si_pid == getpid())
+          DS2BUG("unknown sigtrap code %d", si.si_code);
+
+        // If the value of si_code is <= 0, then the signal was generated by a
+        // user process via kill(2), sigsend(2), abort(3C), raise(3C), etc. No
+        // action is needed other than updating the thread's stop info.
+        DS2LOG(Warning, "sigtrap code %d recieved from %" PRI_PID, si.si_code,
+               si.si_pid);
+        _stopInfo.reason = StopInfo::kReasonTrap;
+        break;
       }
     } else {
       // This is not a signal that we originated. We can output a

Support/Testing/Excluded/ds2/android-x86_64.excluded

@@ -89,7 +89,6 @@ TestProcessAttach.ProcessAttachTestCase.test_attach_to_process_by_id_autocontinu
 TestProcessAttach.ProcessAttachTestCase.test_attach_to_process_by_id_correct_executable_offset
 TestProcessAttach.ProcessAttachTestCase.test_attach_to_process_by_name
 TestProcessAttach.ProcessAttachTestCase.test_attach_to_process_from_different_dir_by_id
-TestRaise.RaiseTestCase.test_sigtrap
 TestRegistersIterator.RegistersIteratorTestCase.test_iter_registers_dwarf
 TestRegistersIterator.RegistersIteratorTestCase.test_iter_registers_dwo
 TestRegisters.RegisterCommandsTestCase.test_convenience_registers_16bit_with_process_attach