[Runtime] Add an option to produce non-symbolicated backtraces.

Symbolication can take some time, depending on the binaries involved.
In certain contexts it's better for the backtrace to finish quickly,
and then symbolication could be done offline.

rdar://122302117

stdlib/public/runtime/CrashHandlerLinux.cpp

@@ -814,6 +814,8 @@ const char *backtracer_argv[] = {
   "true",                       // 28
   "--output-to",                // 29
   "stdout",                     // 30
+  "--symbolicate",              // 31
+  "true",                       // 32
   NULL
 };
 
@@ -923,6 +925,7 @@ run_backtracer(int memserver_fd)
   }
 
   backtracer_argv[28] = trueOrFalse(_swift_backtraceSettings.cache);
+  backtracer_argv[32] = trueOrFalse(_swift_backtraceSettings.symbolicate);
 
   _swift_formatUnsigned(_swift_backtraceSettings.timeout, timeout_buf);