[lldb] Set the stop reason when receiving swbreak/hwbreak (llvm#108518)

xusheng added support for swbreak/hwbreak a month ago, and no special
support was needed in ProcessGDBRemote when they're received because
lldb already marks a thread as having hit a breakpoint when it stops at
a breakpoint site. However, with changes I am working on, we need to
know the real stop reason a thread stopped or the breakpoint hit will
not be recognized.

This is similar to how lldb processes the "watch/rwatch/awatch" keys in
a thread stop packet -- we set the `reason` to `watchpoint`, and these
set it to `breakpoint` so we set the stop reason correctly later in
these methods.

(cherry picked from commit 65a4d11)

Author: jasonmolenda

lldb/source/Plugins/Process/gdb-remote/ProcessGDBRemote.cpp

@@ -2273,6 +2273,8 @@ StateType ProcessGDBRemote::SetThreadStopInfo(StringExtractor &stop_packet) {
         StreamString ostr;
         ostr.Printf("%" PRIu64, wp_addr);
         description = std::string(ostr.GetString());
+      } else if (key.compare("swbreak") == 0 || key.compare("hwbreak") == 0) {
+        reason = "breakpoint";
       } else if (key.compare("library") == 0) {
         auto error = LoadModules();
         if (error) {