Hexagon (linux-user/hexagon): handle breakpoints

This enables LLDB to work with hexagon linux-user mode through the GDB
remote protocol.

Helped-by: Richard Henderson <[email protected]>
Signed-off-by: Matheus Tavares Bernardino <[email protected]>
Reviewed-by: Richard Henderson <[email protected]>
Signed-off-by: Taylor Simpson <[email protected]>
Message-Id: <c287a129dcbe7d974d8b7608e8672d34a3c91c04.1683214375.git.quic_mathbern@quicinc.com>

Author: quic-mathbern

linux-user/hexagon/cpu_loop.c

@@ -63,6 +63,9 @@ void cpu_loop(CPUHexagonState *env)
         case EXCP_ATOMIC:
             cpu_exec_step_atomic(cs);
             break;
+        case EXCP_DEBUG:
+            force_sig_fault(TARGET_SIGTRAP, TARGET_TRAP_BRKPT, 0);
+            break;
         default:
             EXCP_DUMP(env, "\nqemu: unhandled CPU exception %#x - aborting\n",
                      trapnr);